Physics SPM Paper 2 Tips - 89 MODIFICATION and 11 DECISION MAKING ( Question and Answer)

MODIFICATION-SECTION BSoalan ini berada di dalam Section B. Cadangan dan alasan dalam soalan ini juga boleh digunakan di dalam Soalan Section C – Making Decision. Dengan contoh yang diberikan ini akan berupaya meningkatkan kemahiran berfikir pelajar di dalam membuat modifikasi dan membuat keputusan bagi situasi yang diberikan di dalam soalan peperiksaan.Insyaallah.

CHAPTER 1

1. Suitable ruler to use in laboratory

Suggestion ExplanationSmallest size scale 0.1 cm More accurateHigh accuracy Less error in measurementHigh consistency Low relative deviationsPlastic material Avoid parallax errorThin thickness Avoid parallax error

CHAPTER 2

2. Explain the suitability feature of arm exercise equipment.

Suggestion ExplanationSpring made of steel Can withstand higher forceTwo // more spring arrange in parallel The spring system is stifferSpring with ticker wire Wire will not easily breakSmaller diameter coil of spring The smaller the diameter coil less elastic the spring, so the arm

exercise would not so hardChoose large force constant spring Will make strong spring, the spring will stiffer and not broken

easily

suggestion ExplanationUse tight and light suit Less air fractionUse spikes shoes Better grip support while running and prevent slipperyUse thicker mattress Increase time impact , reduce impulsive force . prevent back

injuryThe athlete have to sprint before jump Can increase kinetic energyAthlete have to bend the body during fall Increase the time impact , reduce impulsive force

3. Suggest the suitable cloth , equipment and techniques to improve high jumper athlete and their safety .

4. Explain the characteristic of spring to make baby’s cradle.

Suggestion ExplanationChoose large force constant spring Will make strong spring, the spring will stiffer and not broken

easily.Choose large diameter of wire The larger diameter the stiffer the spring is.Large diameter coil of spring The larger the diameter coil more elastic the spring isThe spring is made of steel or alloy Steel and alloy is stiffer than ironThe arrangement of spring is two or more line in parallel

The spring is stiffer

5. Explain the most suitable design of spring for shock absorber for motorcycles.

Suggestion ExplanationSmall diameter of spring coil Enough space for the springChoose large diameter of wire The larger the diameter the stiffer the springForce constant is more than 1000N Can support motorcyclist and passenger up to 100kgHigher spring constant Small compression of the springSmall natural frequency To reduce bumping, comfortable for user

6. Explain the simple characteristic of the rocket than can travel with greater acceleration.

Suggestions ExplanationsChoose metal with high strength and hardness Even under pressure the shape will not change easilyFrame of rocket is made of low density metal Lighter, can increase accelerationMultistage rocket invented Each stage has burning fuel, pump and combustion chamber. It

will slip off when fuel of each chamber completely burn. When the mass decreases, the acceleration increase

Rocket need to carry a tank of oxygen To enable the combustion of fuel in spaceSilver color rocket Reflect light efficiently so the temperature of the rocket will not

riseCover the body of rocket with heat insulator Friction between air and body will increase heat. The insulator

will reduce heat conductivityAerodynamic shape Reduce air friction, move faster

7. Suggest and explain the build of water bottle rocket in school competition to move higher altitude and has longer time on the air.

Suggestions ExplanationsThe body of rocket must be tough Do not break easily in high pressure and when landingSmaller mass Rocket will accelerate fasterThe shape is streamline/aerodynamic Reduce air resistanceNose cone or bullet shape on top of body To improve the aerodynamic of rocket45 angle of launching The rocket can travel maximum distanceThe volume of water is half or 1/3 from the whole volume

To increase momentum and impulsive force

Attach 3 or 4 fins at the tail of rocket space equally

Rocket will move smooth and stable

Attach parachute will make the rocket floating and has longer time on the air before landing//decrease the speed of falling due to air resistance

8. Give suggestion to improve the design of jet engine so that it can be use for larger airplane at the higher speed.

Suggestions ExplanationsIncrease more fuel injectors More fuel to be burnt to produce greater forceIncrease the size of the combustion chamber More space for fuel to burntDecrease the diameter of the nozzle Exhaust gas ejected at higher velocityIncrease the speed of blade/use bigger blade Increase the air intakeBlade and engine made of strong materials Can withstand strong pressure and won’t break easily

9. Base on the physic principle, suggest the design of roller skate track so it can be use to oscillate skate continuously.

Suggestions Explanations Semi circular curve shape Exchange between kinetic energy and gravitational potential

easilySmooth surface Reduce frictional force/easy to slideThe slope slightly increase and decrease Easy to oscillates cause by changing of energyUse strong material such concrete of foundation of the track

Withstand high impact such as high force of jumping and landing

Soft layer at the surface Reduce impulsive force when landing, low risk if accident

10. Explain the most suitable design of motorcycle that can move fast, safe and save time in racing.

Suggestions ExplanationsLower seat height Lower center of gravity or more stable or safer to turn.Bigger width of tire Bigger surface area, better support or low pressure acts on the

tires or more friction when breaks.Less thread pattern To decrease friction of tires to the road, can move fastSmaller mass Lighter, can move faster or low inertiaWith ABS Motorcycle does not stop immediately or can be controlled if

direction changes or does not move sideways or more friction

with ABS

11. Suggest and explain how to make suitable beach motorcycle which able to move on the sand smoothly and comfortable.

Suggestions ExplanationsDeep thread patter // more definitive pattern Better grip on sand, able to move smoothly on sandLarge tire (big surface contact with ground) Reduce total pressure of car, increase stability and the car

would not get stuck in the sandSoft seat and water resistance Comfortable for cycles and would not get wet easilyExcellent resistance to rusting Everlasting. Would not rust easilyAttach shock absorber with higher spring constant and small natural frequency.

Reduce bumping, comfortable to cycle with

Low density body Lighter, would not stuck in sand

12. Suggest the suitable cloth and the best techniques to catch ball to prevent injury for goalkeeper.

Suggestion ExplanationsWear glove Reduce painful of the player’s hands when touching the ball

with big impulsive force.Use soft material for glove Lengthen the time impact, reduce impulsive force.Wear cloth which is made from material with moderate specific heat capacity

The cloth can absorb more heat when the player is sweating to maintain the temperature of player.

Base of shoes has stud Player give great pressure to make stud sink into ground and give stronger support without slipping.

When catching the ball, the goal keeper should move his hand backwards

This action lengthen the time impact between ball and hand, so it reduce the impulsive force.

The ball should have enough air pressure inside Shorter the time impact between foot and ball, so impulsive force increase then the ball will has high speed and travel far away.

13. Using physics concept, suggest and explain suitable athlete’s attires, running, jumping, landing techniques and

other aspects to help the long jumper can jump further.

Suggestion ExplanationUse tight and light suit Less air friction Use spike shoes Better grip support while running and prevent slipperyThe athlete have to sprint before jump Can increase the kinetic energy//momentumThe athlete have to push the body infront while jumping

Increase the elastic potential energy//able to increase longer distance of jumping

Athlete have to bent the body during fall Increase the time impact, reduce impulsive force, less injured

14. Safety feature in car

Characteristic ExplanationThe bumper of car is prone to crash It will increase the time impact, the impulsive force will reduceThe sitting space of the passenger is reinforced To protect the passengerUse safety belt During collision, safety belt will hold the passengers from

thrown infront due to inertia Use air bag Will inflate when accident occurs, the driver safe from hitting

steering Antilock breaking system(ABS) Allow car to stop quickly on slippery road and prevent from

skidding Strong steel struts Give good protection from side on collisionTire with tread Can stays contact with road, prever slippery

15. Explain the suitable loaded lorry which can carry liquid, such as petrol

Suggestion ExplanationThe load of lorry should be divided into many smaller tank

To reduce effect of inertia

The load must be tied So it will no fall of from the lorryFar gap distances between tractor and trailer Prevent collision between tractor and trailer, easier when

turningUse more tire for lorry Pressure will be separate to all tires, able to carry more loads.

Lower pressure better support and stabilitySmall belt behind lorry To discharge spark, safety reason to prevent from burning the

petrol Use antilock break system (ABS) The lorry can stop easily without skidding

16. Explain the design of and how kayak which can travel faster and safer.

Suggestion ExplanationStreamline /aerodynamic shape of body Reduce water resistanceSmooth surface body /coated with wax Reduce friction of body towards waterLow density material Lighter , easier to float, easy to carry and sail fasterStrong material body and peddle Everlasting , not easily brokenWider peddle surface Greater force because more water are peddled upWear safety jacket Passenger can float and safe if they fall into water.

17. Give suggestion to design a sail boat which can travel faster and smooth.

Suggestion ExplanationStreamline /aerodynamic shape of board Reduce water and air resistance,can increase liftingSmooth surface board/coated with wax Reduce friction toward waterLow density material Lighter, easier to float and sail fasterStrong material Withstand strong wind, not easily damageWider sail Greater lifting force because more wind are captured

18. Modified the ship that can carry more and heavier load, move faster and safe while travelling.

Suggestion ExplanationStrong material Can withstand great forceLow density material Light weightHas more than two stage,plimsoll line Safe to travel on the fresh and salt waterBig size Can place more goodsAerodynamic/streamline shape Reduce water friction.Waterproof sail Sail would not get e=wet easily.

19. Suggest how to increase the safety for motorbike racer to reduce injuries / accidentSuggestion Explanation

Use helmet To protect the headUse helmet with hard outer casing and soft inner liner

Helmet reduce head injuries in a crash by spreading the impact with hard outer casing and absorb energy with soft inner linear of styrofoam

Use safety jacket To protect the from injuries , cut ,burnUse gloves To protect the handUse padded leathers suit Will soften any impact and protect the skin from abrasion

20. An earth-monitoring satellite falls into the earth’s atmosphere at a high velocity and reaches a high temperature. This is caused by the earth’s gravitational force and air resistance.Using the appropriate physics concepts, suggest and explain suitable designs or ways to protect the satellite and its equipment:

Suggestion Explanation

Aerodynamic shape To reduce air resistanceHeat shield / material that is hard to burn To protect the capsuleHigh melting point //ceramic Do not meltLanding in water // air bag Increase time of impact// Reduce impulsive forceLight material / / small mass // low density -Reduce the inertia // -reduce the momentum //

-reduce impuls Paracute / /Retro rocket To reduce speedHard material // stiff composite Not easy to bend

21. Explain how you would design the pile driving system.[the ram hammer is lifted to a height by the crane and allowed to fall on the pile.

Modification ReasonLarge hammer weight Large momentum when it hit the pileRam hammer made from hard material such as alloys

Not break easily/last longer

Hammer raised at higher position Inrease the gravitational potential energyStronger End of the top of the concrete pile To avoid break at the top couse by the hammerSharp End of the bottom of the concrete pile To increase the pressure

CHAPTER 3

22. Efficient brake system

Suggestions ExplanationsType of liquid: oil UncompressibleThickness of brake line :high To counter the high pressure from the liquidThe ratio of cross sectional area for wheel piston and master piston :high

To produce larger force on wheel piston

The chosen of type of brake for front rear wheel:Front wheel - discRear wheel - drum

Disc brake is more efficient than drum brake

23. Explain the design of hydrometer which can be use to determine a wide range of densities of liquid.

Suggestions ExplanationsSmall stem and long Increase sensitivity where the scale division are far apart so

that small changes in density can be detectedGlass wall Do not erode and small adhesive forceLarge diameter of bulb High up thrust / displaces more liquid / able to float easilyScale can be made bigger or smaller than the density of water.[calibration]

- The hydrometer is floated in alcohol. The liquid level at the stem is marked (upper level)

- Then, the hydrometer is floated in higher density liquid like mercury and marked (lower level)

Ability to measure a wide range of densities of liquids.

Lead shots Hydrometer can stay upright

24. Describe the suitable design to build mobile tent for Sure Heboh event which will be construct at open space for a week. Using appropriate physics concept, suggests and explain.

Suggestion Explanation

Choose low density metal for frame Light weight and strongUse hollow rod which can assemble easily Hollow rod is not heavy, but equally strong, easy to mobile

anywhere, faster to build, can reduce the cost of construction and transport

Water proof canvas If raining, would not getting wetAnti rust rod Can withstand rain and long lastingSharp end rod Small surface area, so higher pressure to ground, yet the

tent can be planted into ground firmly and stand still

25. Explain the necessary modification for the structure of dentist chair for children that are suitable and save for the adult.

Suggestion ExplanationIncrease the cross-sectional area of big piston and decrease the cross-sectional area of small piston

To increase the output force acting on big piston / to lift havier adult / to increase force multiplier of system

The wall of pipe is made up of strong alloy to hold the fluid

To withstand the strong pressure that might cause cracking in the channel

Change the less control into electric touch control To lift or lowered the chair to the desire weight more easily and safety

The surface area of the seat enlarged To support the people with the large bodiesUse non-corrosive oil in jack So that the wall of the pipe will not be controlled and cause

leakage

26. Explain the build and design of hot air ballon wich can fly higher altitude faster and suggest some safety aspect.

Suggestion ExplanationLarge ballon Produce bigger buoyant / upthrust force, increase the

volume of air displacementMany hot air burner Heat up the gas inside fasterSynthetic nylon ballon Air proof, light weight and strong materialGas temperature is high Reduce the density of air in ballonTotal of mass is low Ballon move upward fasterRattan basket Longer the time impact, reduce the impulsive force to

passanger when landingFly on early morning or late afternoon The temperature outside the ballon is cooler compare to

the inside of ballon, so the ballon will rise higher

27. Explain the basic structure of small submarine that can be use for underwater exploration.

Suggestion ExplanationStrong material Does not break easilyAerodynamic shape Reduce water resistanceThick wall Water pressure increase with depthHigh density materials Increase mass / can submerge easilyBallast tank To increase or reduce weightSonar transmitter and receiver To estimate and depth

28. Suggest the design of submarine which can submerge and float in the sea.

Suggestion ExplanationBallast tank are partially filled with water The submarine will partially floatAerodynamic // streamline body To reduce water resistanceUse hard and stiff materials for body To overcome the pressure of water in the seaAttach periscope To view surrounding area when submarine floatUse nuclear power sources to generate power Cheap and lasting power

29. Explain the characteristic of material to be use for making the sole of jungle trekking shoes.

Suggestion ExplanationRubber sole Good impact absorber

Low density Light weightMany stud Give extra gripLow expansion effect Not loose easilyExcellent ability of stretch Comfortable to feet, foot can move unstressed

30. Using physics concept, explain necessary deep sea diving suit and other accessory to carry.

Suggestion ExplanationChoose strong helmet with thick metal and glass to cover head

To withstand high pressure of water and protect the head

Use thick glass in front of diver face Enable the diver to see surrounding and at the same time able to withstand the pressureof water

Use water proof suit and able to withstand pressure Due to depth, the pressure under water is very high

Bring along gas containing mixture of oxygen To provide oxygen to diver for breath

Use very heavy suit The diver enable to stand on the floor of ocean and able to fight buoyancy of water

31. Modified the passanger airplane to cargo airplane that needs to carry more laod, less use of fuel, effenciency and safety to travel.

Suggestion ExplanationIncrease the size of the body To increase the spaceIncrease the length of the wing To increase the upthrustIncrease the thickness of the body To stand higher pressure differenceUse a more powerful engine To overcome bigger inertia and do more work per unit timeIncrease the number of tyres To support higher mass or pressure while landingProtective bar between the cabin and the pilot To prevent moving object to knock at the pilot while

landingPilot has ejected seat during emergency To save the pilot if plane crash happened

32. Design Vacuum Cleaner

Suggestion ExplanationLarge fan driven Inrease the spped and amaunt of airflowsPowerfull of lectric motor Inrease the spped and amaunt of airflowsNarrower inlet opening Inrease the velocity/decrease air pressureUsing a very large filter to block dust particles while allowing air moleculs to pass through

To have a lots of surface area and many pores for air to flow through

Larger spaced for depositing and collecting the dust particles

Ensure that the air flows through the filter is not block by too many dust particles

33. Design paint sprayer

Suggestion ExplanationLarge size of air vessel Compress more air/can exert large pressureRubber material for the vessel More elastic/easier to squeezeNarrow shape of the tube Air can move with high speedFibre glass material for the rod Stronger and last longerSize of nozzle is narrow at the end The paint can be sprayed evenly

34. Design hidraulic jack

Suggestion ExplanationBigger crossectional area of slave piston(big piston) Produced higher force

Small crossectional area of master piston(small piston) Less forced is needed/produced bigger pressurreLonger handle Less forced is needed to press small piston(master

piston)Low density of a body LighterOil for liquid Non-compressableRelease valve between small and main reservoir(reset) Liquid can flows into small reservoir easily when push

the reset button.

35. Design hydrometer

Suggestion ExplanationBulb with lead shot at the lower section To submerge the hydrometer and not overturnCylinder with bigger diameter at the bottom not overturn/increase stabilityCylinder with smaller diameter at the upper section A small reading scale can be incorporated/inrease the

sensitivitySmaller scale inrease the sensitivityFilled with air Inrease the beyoncy forceGlass wall Not corrode easily

CHAPTER 4

36. Most suitable design of thermometer to use in Antarctica

Suggestion ExplanationUse alcohol as liquid – in glass thermometer Freezing point of alcohol is -115oC .So , it will not freeze

at low temperatureUse thin wall of bulb So it will sensitive to the change of heatUse small diameter of capillary tube Alcohol can expand at high rate for the small change in

temperatureUse thick glass wall The loss of heat to surrounding is smallUse round glass stem Can act as magnifying glass , so the alcohol level can be

seen clearer

37. Most suitable design of clinical thermometer

Suggestion ExplanationUse mercury Easy to read because it colour and opaqueThe scale range from 35oC to 42oC To measure human body heatSmall diameter of capillary tube// extra fine bore tube

Mercury can expand at high rate for a small change in temperature

Use thin glass wall of bulb Sensitive to change of temperatureUse round glass stem and wall Can act as ,magnifying glass. So, mercury can be seen

clearly

38. Explain the design and the characteristics of the cooking pan

Suggestion ExplanationBase is made of a copper Copper has a lower heat capacity it become hot very quicklyHigh density of base Heavier base make the pot stable and not topple over easilyBody is made of aluminium Low specific heat capacity becomes hot very quickly but it

low density make it overall weight of weight lighterHandle is made of wood or plastic High specific heat capacity so the handle do not become hot .

SafeChoose low density material for handle Does not add much to the total weight of potTransparent pot cover Able to cooker to see the food. Food cover will trap the heat

39. Suggest and explian the design of water heater to boil a large quantity of water faster ,efficient and safely

Suggestion ExplanationUse tungsten High melting point,high heat energy

Coiled Longer wire,increase the resistanceHigh melting point Not easy to melt at high temperatureLower rate of rusting Does not get rust easilyUse thermostat When temperatures reach 100 Celsius, the water heater

will automatically turn off

40. Determine the modification to be made for container,so the cut fruit will keep cool, remain fresh and easily seen by customers.

Suggestion ExplanationUse container with high specific heat capacity Able to slow down the loss of heat from the containerPlace small ice packet below the bottom of the cut friuts

The cut fruits is chill and juicy, ice able to absorb a large amount of latent heat when melt

Add salt to the packet of ice Foreign matter will increase the freezing point of ice, so this will slow down the ice from melting

White wall colour of container Can avoid absorbtion of heat from the surroundingThe container has double wall Avoid heat from surrounding transferred easily to

container. The inside container remains coolTransparent wall of container in front of customer The customer can see and choose the cut fruits easily

41. Investigate the most suitable liquid that can be use as coolant for car engine using physics concept.

Suggestion ExplanationLow freezing point liquid Will not freeze easily during winter weatherHigh boiling point liquid Do not easily boil when absorbing heat from the engineHigh specific heat capacity liquid Can transfer large contain of heat with a small rise in

temperature. Able to cool up the engineLow ability to react with metal The metal part of the engine will not corrode easily

42. Most suitable thermometer for laboratory to measure the temperature of ice and boiling point of water

Suggestion ExplanationSize of the bulb is small Does not need a lot of heat to heat up the mercury to

expandUse thin wall of bulb So it is sensitive to change of heatUse mercury Freeezing point of the mercury is -39 degree celsius and

boling point 357 degree celsius . Able to has a range from -10 to 110 degree Celsius. Mercury can expand a high rate for small change of temperature

Use thin wall capillary Able quick heat transfer from the surrounding to the mercury. So, the thermemeter is more sensitive

Has minimum size scale with small division Making thermometer a sensitive instrument

43. Modified and explain the design of an efficient solar water-heating system on the roof.

Suggestion ExplanationPipe embedded in plate must be long Longer pipe will has greater surface area which can

absorb heat fasterUse metal pipe as pipe inside the plate Metal is good heat conductor , so heat will easily

transmit to waterUse insulator behind the absorber panel Insulator will prevent the heat lossUse black absorber panel Black is good heat absorberCover the top of the panel with glass Heat will trap inside due to green house effectPut the tank at higher level To give higher pressure

44. Explain the build of solar cooker oven that been use in science month competition at your school to boil 500ml water in short time.

Suggestion ExplanationBuild the solar cooker with shiny// silver colour The light will reflect to the cooker and heat up the water

reflector insideUse metal cooker Good conductorPaint the outside part of the solar cooker and the cooker ( contain water ) with black colour

To absorb

Wrap the cooker with plastic or glass Avoid heat from release to sorroundingTo trap heat, the temperataure will increase To absorb heat, the water boil faster

45. Suggest the design of heating system in the house and characteristics of heating agent. The house use central heating system with boiler, radiator and pipelines.

Suggestion ExplanationUse strong material Not easily breakUse metal pipe with good heat conductor Increase the rate of heat transferIncrease length of cooling coil Can transfer the heat faster to surroundingUse greater boiling point liquid Liquid not easily change into vapourLow rate of rusting material Long lasting, not easily rustThe bigger size of radiator fan Can blow and cool down larger areaPipe in coil structure is used Increase the time of floe and increase the quantity of haet

transferred.

46. Suggest the characteristic of material to build food container which can keep the food warm.

Suggestion ExplanationFood container should made of low density material

Lighter , the container able to be move from one place to another.

Melting point of container should be high To prevent the container from melting up when hot food is store inside

Specific heat capacity should be high So the container will not get hot easily. Safe to touch and handle.

Thermal conductivity is low.i Good heat insulator , to ensure the heat not loss and the food remain hot.

Double wall To prevent hest loss.

47. Explain the characteristic and design of thermos flasks to maintain hot water.

Suggestion ExplanationUse hollow plastic stopper Able to trap air as air is poor heat conductor.so,less heat

loss through stopper.Vacuum space Prevent heat loss through conduction or convectionHas double wall Has vacuum in between heat not easier pass through the

wall of thermos.Double walled tube coated with shiny paint Shiny surface reflect heat from the wall of thermos flasks

back to water.so the water remain hot.Double walled made of glass Glass is bad conductor.it will reduce heat loss.

48. Explain how the design of radiator of the car and characteristic of cooling agent which can absorb heat at short time,

Suggestion ExplanationIncrease the length/area of cooling coil Can transfer the heat faster to the surroundingIncrease the number of fin blades Can cool down fasterUse larger fan Can cool down larger areaUse cooling agent liquid with greater boiling point It won’t boild easily in high temperatureUse cooling agent liquid with higher specific heat capacity

Able to absorb large amount of heat

CHAPTER 5

49. Determine and explain in the build of magnifying glass to be use for enlarging the image of stamp

Suggestion Explanation

Choose convex lens The image will magnifyExcellent clarity of lens The image is clearerSmall focal length Able to focus nearerMedium diameter of lens Able to be hold by hand to identify the stampsThe object is place less distance than focal length The image form is magnify, virtual and upright

50. Explain the suitability of the mirror that be use in shop to watch over the customer

Suggestion ExplanationUse convex mirror Wider field of viewGreater reflectivity of material Clearer image Choose a bigger size of mirror Enable wider view and sharper imagePlace the mirror at the corner of shop ceiling Easier to look at and won’t disturb the customer pathwayLow density Lighter to hang up

51. Design fibre optic

Suggestion ExplanationUse refractive index of outer layer is less than the refractive index of inner layer

So that total internal reflection can happen in the fiber optic.

Use high flexibility material so that it can be bend easilyUse strong material do not break easilyUse thin material Lighter // can be use in small areaLow density material Lighter

52. Determine and explain the build of microscope using lens P and Q with focal length of 15 cm and 5 cm respectively. Suggest modification that need to be done to get brighter ang bigger image.

Suggestion ExplainationP as eye piece and Q as objective lens Focal length of P is longer than QFo < u <2fo To produce real, inverted and magnified imageAdjusted so that u < fe To produce virtual. Inverted and bigger image// to acts as a

magnifying glassDistance between lenses > fo + fe To produce bigger image from the eyepiece // to increase

the magnificationStore in a cool and dry place To avoid formation fungus at the lensesUse more powerful// shorter focal length lenses To produce bigger imageUse a lamp near the object// use bigger diameter of objective lens

To produce brighter image

53. Explain the suitable characteristic of the mirror to be use as outdoor safety mirror at the corner of the road

Suggestion ExplanationUse convex mirror Wider field of viewExcellent weather resistance Able to withstand bad weatherExcellent impact resistance of material Save cost, everlastingBigger size mirror To enable a wider view and sharper imageGreater reflectivity of material Clearer image even in bad weatherPlace at the sharp road corner , at bending road To minimize from accident occur, to enable motorist see

the oncoming trafficSmall roof Protect from rain drop for better image

54. Detemine and explain the build of Astro disc using appropriate physics concepts.

Suggestion ExplanationChoose convex curve parabolic The signals come can be focus at one pointAll signal are focus on focal point Better reception

Smooth surface of disc Better reflectionLocate the disc at high and facing towards satellite No obstacle, better signalClean surface of disc, no water drop or dirt Better reflection, almost 100% reception receive by feed

horn

55. Modified the slide projector that need to be place in school hall and can be seen by many student with clearer image.

suggestion ExplainationUse higher power bulb Higher intensity of light or more light producedThe filament of the bulb is at the focus point of the concave mirror

The light focuses at one point. // parallel ray can be obtained after reflection by concave mirror

More curvature More light to be reflected (upward) // less light toward other direction other than upward

Lens between f and 2f To produce real ang enlarge or bigger imagesIncrease the distance or further away the screen Larger image producedElectric fan operates during and after the lamp is switches on

Cooling system to stabilized the temperature (heat energy produced by filament bulb) to increase the projector lifetime

Use condenser mirror To concentrate more light to the slideUse a concave mirror instead of plane mirror Focus the light directly to the lens // increase the intensity

og lightPlace the filament at centre of curvature of the converging mirror // use high powered lens

Light goes directly from the lamp and reflect back on the same path // increase the intensity of light toward the transparency // to get brighter image

Use heat filter To absorb excess heat to the transparency

56. Determine and explain the build of telescope using lens J and K with lens K is thicker than lens J which produce bigger and clearer image.

Suggestion Expalanation C hoose lens K as eyepiece lens

Lens K is thicker than lens J Light ray is refracted more in lens K than lens J, focal

length of lens K is shorter than lens J Therefore the thickerthe lens, the greater the

refraction of light and with that the shorter the focal length of a lens will be

Choose lens J as objective lensUse bigger diameter lens as objective lens

Characteristics of objective lens for telescope is Has larger surface area which allow more light

enter Has a longer focal length

Use low power convex lens as the objective lens Magnification of telescope =f0/feLow power lens has a longer focal length ,fo higher, magnification higher

Use high power convex lens as the eye lens High power lens has a shorter focal length,fe higher, magnnification higher

Use bigger diameter of objective lens More light permitted to enter the telescope and a clearer image is seen

CHAPTER 6

57. Design a good beach

Suggestion Explanation

near the bay divergence of the waves energy /calmerHigh retaining walls Over flow

To reflect the waves from the shoreReduce direct impact of the waves on the shore

Wall from concrete reduce erosion are builtConcrete barrier structure with a gap Waves passing through the gap will be diffracted in the

children’s area.-reduce amplitude

Tambak laut supaya lebih cetek Reduce speedMore number of tree Diffraction occur will reduce tha amplitudeUneven surface of retaining wall Reduce energy

58. Suggest and explain how ordinary fishing boat can be upgrade to the new boat which complete equipment to detect the crowd of fish.

Suggestion ExplanationAttach radar system to the ship

a) Ultrasonic transmitter

This equipment needs to detect crowd of fish and for measurement the depth of the crowd of fish-Use to produce ultrasonic pulses

a) Microfone reciever To detect ultrasonic pulsesb) CRO -To measure the depth of fish by calculating d=vt/2;

d=depth, v=velocity, t=timeUse ultrasonic wave -Ultrasound not produce sound

-Ultrasonic wave has higher frequency, more energy, so it can move further

Use high energy wave The penetrating power is higher

59. Explain the suitable design or method to build quality concert hall.

Suggestion ExplanationCover the hard wall with soft board or thick curtain Soft surface can absorb sound and reduce reflection of

soundPlace the wall with hole or egg carton design Can reduce reflection of sound so sound will be

clearer/reduce echoFixed 2 loud speaker in concert hall Loud speaker can act as coherent sources for

constructive inteferenceArranged the sit at antinodal place Strong sound can be heardUse glass or mirror hall which is the type which are not easily broken

Sound with high frequency might break the glass

Use special computer to generate sound wave which produce destructive inteference

Audience can enjoy better presentation without disturbance

60. Explain the suitable design of retaining wall to protect the ship at the harbor

Suggestion ExplainationBuild concrete retaining wall Can withstand impact of the wave, difficult to crackRetaining wall should be curved and uneven surface Prevent reflection of wave back to the shipBuild retaining wall in front of the bay The wave are calmer at thr regionRetaining wall has gap Diffraction will occurThe gap at retaining wall is narrow( smaller than wave length)

The greater the curvature of wavefront will occur. Amplitude after passing gap is smaller

There are slope at the bottom of retaining wall At shallow region, the wavelength of wave is smaller, so the velocity of the wave smaller

Retaining wall should be build higher To ensure no spill over of waveBuild the jetty at bay The wave at bay is calmer

61. Explain the characteristics of parabolic radar system to detect signal from satellite communication.

Suggestion ExplanationLarge diameter size of parabolic disc Able to receives more electric signalType of wave transmited is Microwave Has high frequency, high energy, short wavelength so it

is easy to be reflectedThe distance of the signal receiver from the centre of parabolic disc is the same as the focal length

The signal can be focus to the centre of the parabolic disc

Place parabolic disc higher from the ground The signal with not be block by trees or anything and the signal easy to be detected

Place parabolic disc at clearplace No signal disturbance

CHAPTER 7

62. Suggest the suitable lamp that can be use in the library, cheaper yet become the room brighter

Suggestion ExplanationLamp with parallel circuit If any lamp were burn out, others can still be usedAttach shiny reflector Can reflect light more, no need to install more lamp, the

room will become brighter.Low power lamp Safe costHigh efficiency lamp // fluorescent The room looks brighterLong life span lamp No need to replace oftenLow price lamp Save money

63. Explain the modification of menthol bulb lamp to efficient lamp to be use in study room.

Suggestion ExplanationUse the fluorescent lamp not a filament bulb Fluorescent lamp use less power and economic (consume less

power) compare to filament bulb.Bigger cover with white colour Less reflection on eyes and absorb less heat energy and good

heat reflectorUse the adjustable stand or portable The height of the lamp can be adjusted can be used anywhereConnect with the earth wire Avoid short circuit and damage on the bulbUse an energy saver lamp Produce same brightness with less power consumption

64. Suggest the suitable design of fuse to protect an electrical equipment which is label 240V,2400W

Suggestion ExplanationThin fuse wire Less space/to carry a limited electrical current/less mass

hence low heat capacity/shorter time to heat up to melting point and blow

Ceramic cartridge Can withstand higher temperature because spark created by high voltage.240V can be huge

Fuse rating is 13A Maximum rating must be sligthly higher than normal currentLow melting point For fast blow/melting faster when excessive current flow/easy

to cut the current flowLow specific heat capacity The fuse wire easily heated,melt and break the circuitMetal is used Good electric conductorResistance to oxidation Does not interface with other function

65. You have to choose one of the cables to be used in the National Grid Network. Explain the suitability of each of the characteristics of the cables.

Suggestion ExplanationDiameter should be large To reduce the resistance of the cabledensity should be low The cables will be lighter and can be supportedsecurelyThe rate of expansion should be low So thre is less expansion and less sagging in the cables during

hot daysThe melting point should be high So the cables does not melt in high temperature

66. Explain the characteristic of electric pylon and the cable taht been use for electric transmission

Suggestion ExplanationMaterial: steel alloy Strong,will not break easilyV shape steel alloy Not too heavy

Trust and supprt join Can support bigger weightMade from small diameter and laminated wire Reduce addy current Cable made from low density material Cable is not heavy/ light weight

67. Investigate the characteristic of electric oven that can toast more cupcakes at less time

Suggestion ExplanationThe space inside oven is build bigger It can fil up 180 slices of breadIncrease the number of resistance heater at the top and bottom

So it can supply enough heat

The wall is made of good insulator Tyhe heat will not lost to surroundingFix a fan inside the oven Heat energy releaswed can spread uniformly in ovenInternal space of oven is painted silver So the heat will radiated at wall and reflected back

completelyFix the step up transformer Oven can receive higher voltage and can function with

higher power 68. Explain the designof electric kettle

Suggestion ExplanationMaterial of heating is made from nichrome To produces high heat energyHigh number of loop To increase surface area so that more heat is releasedUse high power To produce more heat energy in the coilHigh melting point coil Nit easy melt under high temperatureLow rate of rusting Does not get rust easilyUse thermostat When temperatures reach 100oC3 plug in If short circuit the overload current flows to earth(for

safety reason)

69. Design incubator used to hatch eggs

Suggestion ExplanationParallel circuit When one bulb damage the another bulb still function/heat can

distributed uniformlyMulti storey rack More eggs can be arrangedUsing fan heat can distributed uniformlyBulb with same brigthness and power heat can distributed uniformlyUsing alarm To ensure that correct timing is employed in the hatching of eggs

70. Design circuit for cabin or house

Suggestion Explanationconnected in parallel Allow each electric appliances to be switched on and off

independently Fit fuse at the live wire in the fuse box To stop the flow of current by melting when a high voltage

of electric current flows through the circuit // switches itself off very quickly if the current exceeds e.g. 15A (for 15A mcb)

Earth connection to the metal case of electrical appliances

Earth wire connected to earth, so that when a fault occurs and a current flows through the live wire and the earth wire, the fuse in the live wire will blow and cut off the supply. It will protect a person who may touch a faulty or live appliance

Use low power lamps / install fluorescent lamp To save the energyRegularly cleaning and removing dust from the air filters of air conditioners// Do not put more water in a kettle than needed for hot drinks

To save the energy

CHAPTER 8

71. Suggest modification that need to be done on dc motor to increase efficiency of the motor.

Suggestion Explanation

Low density material Coil hass smaller mass/ lighterIncrease the number of turns in the coil

Can increase magnitude of force/ higher electromagnetic field strength

Use high strength of magnets/ Add more magnets

Increase the strength of magnetic field

More segments Coil rotates smoothlyIncrease the magnitude of current

Can increase the magnitude of force/ can increase the strength of magnetic field

72. Investigate the design and the characteristic to improve the efficiency of transformer.

Suggestion ExplanationUse soft iron core Easy to magnetized and demagnetizedLaminated core Less eddy current or reduce energy lostUse thick wire Reduce the resistance or more current flowUse copper wire to make coil Low resistance or reduce the lost of heatWind the secondary coil on top of the primary coil Reduce leakage of field lines

73. How to design a moving coil ammeter that can function better and able to detect small change of current?

Suggestion ExplanationUse stronger magnet Strong magnetic field or larger rotationUse curve magnet or concave Produce radial magnetic field/to get linear scaleUse cylindrical core To supply uniform magnetic fieldUse soft iron core To concentrate the magnetic fieldUse linear scale The angle of rotation is linearThe sensitivity of moving coil galvanometer can be increased by increasing the strength of the radial magnetic field

Increase the force between the current carrying coil and magnetic field

Using hairspring of lower stiffness Smaller opposing force to stop turning of coilUse lighter pointer Smaller inertia easier to moveUse a coil of a lighter mass Smaller inertia able to move easilyIncrease the area of coil More changes of magnetic flux,a bigger force are produce

74. Suggest and explain the build of adaptor to charge the 8V handphone from 240V power supply.

Suggestion ExplanationUse step down transformer Able to reduce voltageRatio of turns 30 : 1 // 240V:8V Can reduce voltage from 240V to 8VUse four diodes Full wave rectificationFull wave rectifier To convert au current to dc currentUsing a capacitor To smooth output current (steady direct current

CHAPTER 9

75. Suggest and explain the build of adaptor to charge the 8V handphone from 240V power supply

Suggestion ExplanationUse step down transformer Able to reduce voltageRatio of turns 30 : 1 // 240V:8V Can reduce voltage from 240V to 8VUse four diodes Full wave rectificationFull wave rectifier To convert au current to dc currentUsing a capacitor To smooth output current (steady direct current

76. Consult and modified the automatic switch light (diagram A) above which can switch on at night and switch off during morning to be automatic switch on fire alarm when there are fire , explain using diagram and the function of component.

Suggestion ExplanationChange R1 to termistor Thermistor can be detect heat from fireChange LED with alarm// siren Able to produce sound of alarm if fire is detectedChange LDR with R1 During fire, R1 has greater resistance compare to LDR so,

no current flowWhen the temperature is high, the resistance of thermistor is low. This will increase the voltage acroos R1. So, currnt will flow to the base of transistor , than the transistor is switch on followed by greater increase in collecter current. The alarm will switch on.

77. Suggest the modification need to be done to the circuit in Diagram C so that it can function as automatically fire alarm switch that need high voltage.

Suggestion ExplanationReplace LDR with thermistor To detect heat when temperature is highReplace bulb with siren/bell To produce soundConnect relay switch to output transistor To switch on the sirenInterchange the position of resistor R and thermistor To increase base voltage//voltage across R//base currentUse 240 V power supply Siren is function as high voltage

78. Modified the circuit 240V and Np = 4000 turns circuit to switch on 12V d.c radio.

Suggestion ExplanationStep-down transformer Capable of reducing potential difference / voltageRatio of turns 20 :1 // 240:12 Np = 4000 turns and Ns = 200 turns

Reduce potential difference 240V to 12V

Using four diodes Full wave retificationUsing a capacitor To smooth out output current // produce output to

steady direct current.

79. Moving coil microphone

Suggestion Explanationuse thin diaphragm Easy to vibrateUse strong material Not easy to breakMore number of turns of coil Increase the rate of change of magnetic flux linkage // The

magnitude of the induced current or is also increasedThicker diameter of wire of coil reduce the resistance of the coilUsing more powerful magnet to increase the strength of the magnetic field.//Increase the rate

of change of magnetic flux linkage//The magnitude of the induced current or induced electromotive force is also increased

12V,24W

CHAPTER 10

80. Explain the suitability of characteristic of radioisotopes to be used as treatment in brain tumor radiotherapy?

Suggestion Explanation Short half life Radioactive is dangerous substance, short half

lfe can decay fasterGamma ray radiation Gamma can kill cancerous cell and can penetrate

skin of patientLow ionozing power Minimum damage to tissue organLiquid state of matter Easy to dissolveHigh penetrating power Can penetrate easily

81. Suggest and explain the safety ways, which are required when handling radioactive substance.

Suggestion ExplanationUse thick lead box Radioactive rays evem gamma cannot pass throughUse forceps / robotic hand Avoid direct touchWear photographic film Able to detect exposure radiationsWear plumbum safety suit To protect the body from expose to radiationUse siren Faster warning when leakagePacked into concrete drum and buried underground Prevent the radioactive waste discharge to environmentAlways place GM detector nearby To detect the amount of radioactive nearby, for safetyLabel the radioactive container with symbol Easy to detect radioactive substance

82. Explain the suitability of characteristic odf radioisotope to be use in controliing the population of pest

Suggestion ExplanationUse gamma ray Able to mutate the insectSolid state of matter Easy to handleLong half life Last longerHigh penetrating power Able to penetrate thick object/materialHigh ionizing power Able to change// mutate the biology of insect

83. . Explain the suitability of characterisitc of radioisotopes to be used in th trace of water pipeline.

Suggestion ExplanationShort lhalf life Radioactive is dangerous substance, short half life can

decay fasterFew hour half life - Enough time for worker to detect the pipe

leakage- Radioactive uis dangerous

Beta particle or Gamma ray radiation Can penetrate pipe and soil, can be detectedLiquid state Can be inject and dissolve into water

84. Suggest the design of nuclear reactor.

Suggestion ExplanationUse uranium-235 Use as nucler fuelNuclear fission A lot of heat will produceBoron or Cadmium rad use as control rods To control the rate of nuvlear fission and to stop the radiationUse moderator (graphitr) To slow the motion of neutron to the best reaction rate. So

the rate of nuclear fission can be controlledBulid thick concrete wall Lead or thick concrete wall can prevent the escape of

radioactive rays, keep the radiation inside the reactorCoarbon dioxide or water is use as coolong agent To remove heat of reaction for turbine generator. This

produce steam as heat carrierUse steam To turn the turbine and able to generate current

85. Explain the suitability of charactersitic of radioisotopes to be used in sanitiza medical equip,ent

Suggestion ExplanationGamma ray Able to kill ant virus/ bacteriaLonger half life No need to change radioactive frequentlySilid state of matter Easy to handleHigh penetrating power Able to penetrate any equipment to sanitize

86. Explain the suitability of characteristics of radioisotope to be used in detecting the position of blood clot in veins (Deep vein thrombosis)

Suggestion ExplanationUse liquid state of matter Able to inject into patient body, dissolve easilyShort half life Active in body in short timeUse beta ray Able to penetrate skinLow ionizing power Minimum damage to tissue organ

87. Explain the suitability of characteristics of radioisotope to be use in the trace of blockage in the kidney patient.

Suggestion ExplanationUse Iodine-123 Used as nuclear imaging tracers to evaluate the anatomic

and physiologyc functionGamma ray Able to penetrate trough body, bones and be detectedLow energy Do not cause serious damage in cellsLiquid state of matter Easy to inject to patient bodyShort half life Active in body in short time

88. Explain the suitability of characteristics of radioisotope to be use in control the thickness of paper in factory

Suggestion ExplanationLong half life Can be used for long time, no need to replace frequently so,

it save costBeta ray Can penetrate paper and be detectedSolid state of matter Easy to handle

89. Explain the suitability of characteristics of radioisotope to be use in control the thickness of aluminium sheet in factory.

Suggestion ExplanationLong half life Can be used for long time, no need to replace frequently7

so, it save costGamma ray Can be penetrate aluminium sheet and be detectedSolid state of matter Easy to handle, does not spill

MAKING DECISION-SECTION CSoalan ini berada di dalam Section C. Cadangan dan alasan dalam soalan ini juga boleh menggunakan contoh jawapan dalam soalan Modification.

90. The transmission of electricity over the National Grid Network uses high voltage cables. You are assigned to study the characteristics of cables which could be used as transmission cable. Table 12 shows the characteristics of four transmission cables. Determine the most suitable transmission cable to be used and give reasons for your choice.

Cable Resistivity /Ωm-1 Density / kg m-3

Cost Rate of thermal expansion

P 3.0 x l0-7 5 x l05 Low HighQ 1.8 x l0-8 2 x l03 Medium LowR 7.5 x l0-7 8 x l02 High MediumS 7.0 x l0-8 4 x l03 Medium High

JawapanCharacteristic Explanation

Low resistivity To reduce heat loss in the cables Low density The cables will be lighter Low cost Cost of project will be lower Low rate of thermal expansion The cables will not expand under hot weather Cable Q Low resistivity, low density, medium cost, low rate of thermal

expansion

91. You are required to build a hydrometer that can be used to measure densities of concentrated acids.Table 11.1 shows the characteristics of 4 types of hydrometers L, M, N and O. Decide which hydrometer is most suitable and give reasons.

Hydrometer Type of material of hydrometer

Diameter of capillary tube/ cm

Density of shots/ kgm-3

Diameter of bottom bulb/ cm

L Plastic/Plastik 0.5 1000 1.0M Plastic/Plastik 2.0 1300 3.0N Glass / kaca 0.5 9800 3.0O Glass/ kaca 2.0 8000 1.0

JawapanCharacteristic Explanation

Material made from glass Glass does not corrode with acidSmall diameter of capillary tube To increase the sensitivity of the hydrometerHigh density of shots Makes the hydrometer stays uprightBig diameter of bottom bulb To obtaine a bigger upthrust.Choose N N is made from glass, has small diameter of capillary tube, high

density of shots and a big diameter of bottom bulb

92. As a researcher , your duty is to study the characteristics of a material to make a water heater. You are given four choices of metal type T, U,V and W. The table below shows the characteristics of the four metals.Determine the most suitable metal to be used as the material to make the heater and give your reasons.

JawapanCharacteristic Explanation

Smaller surface area the resistance is higherHigh melting point not easy to meltLow specific heat capacity the temperature arises shortly

Metal The cross sectional area Melting Point Specific Heat Capacity LengthT Smaller Low High LongU Larger High Low ShortV Smaller High Low LongW Larger High Low Short

Long (coiled) metal to increase the resistanceChoose V because it has,smaller surface area, high melting point, low

specific heat capacity and long metal

93. You are given four choices of metals P, Q, R and S. The table below shows the characteristics for the four metals. Determine the most suitable metal to be used as the material to make the boat and give your reasons.

Metal Shape Density Specific Heat Capacity

Strength

P Streamlined 900 Low HighQ Oval 452 High HighR Circle 387 Low HighS Streamlined 500 High High

JawapanCharacteristic/cirri Reason/Sebab

Streamline / larus reduce the resistance of water/ Density /ketumpatan rendah higher buoyant force/ daya apungan tinggiSpecific heat capacity high / absorbs heat slowly/serap haba dengan perlahanHigh strength / Kekuatan tinggi Difficult to damage / sukar rosak Choose S because its streamline,low density, high specific

heat capacity and high strength 94. A student plans to fix a lamp in his room. Table 12.1 shows the features of 4 different types of lamps. Explain

the suitability of each feature in Table 12.1 and then determine the most suitable lamp to be used. Give a reason for your choice

Type of lamp Power Efficiency Life Span PriceCompact fluorescent lamp 18 W 50 % 7000 hours HighFilament lamp 75 W 12 % 1000 hours LowLong fluorescent lamp 20 W 45 % 14000 hours MediumRound fluorescent lamp 24 W 40 % 10000 hours High

JawapanCharacteristic Explanation

Low power lamp Safe cost//electric billHigh efficiency The room looks brighter//high output power//less power

wastageLong life span No need to replace oftenLow price Save money/costLong fluorescent Low power with highest efficiency, long hours of life span and

low price

95. Table 11.1 shows 5 materials which can be used to make an optical fibre. You are asked to investigate the characteristics of the materials in Table 11.1 which could be used to make the optical fibre.Explain the suitability of each characteristic and hence, determine the most suitable material to be used to make the optical fibre. Give a reason for your choice.

Material Refractive index % of light energy absorbed Rigidity Strength

P 1.75 2 % Strong WeakQ 1.80 10 % Weak StrongR 1.70 2 % Weak StrongS 1.52 3 % Strong StrongT 1.48 10 % Weak Weak

JawapanCharacteristic Explanation

High refractive index Total internal reflection can occur easilySmall amount of light energy being absorbed The object under observation can be seen clearly // more light

by the material can be transmittedMaterial with weak rigidity The optical fibre can be bent easilyMaterial with great strength The optical fibre can last longer/not easily spoilMaterial R High refractive index, low % of light energy absorbed, weak

rigidity and great strength

96. You are asked to investigate the characteristics of hot air balloon as below. Explain the suitability for each characteristic for the hot air balloons and then determine which hot balloon will move up the fastest into the air. Give a reason for your choice

JawapanCharacteristic Explaination

Volume of the balloon is high Displace a larger amount of air/Produce a higher buoyant force.

Density of the balloon material is low Lower mass/LightGas temperature is high Produce a maximum expansion of balloon.Total of mass is low Upwards resultant force is higher/ Balloon move upwards faster.

Choose QBecause it has a high volume,the density of the balloon material is low,the gas temperature is high and the total mass is low.

97. Table 11.1 shows the characteristics of five types of materials that can be used for making the soles of the trekking shoes. You are asked to study the characteristics of the materials shown in Table 11.1. Explain the suitability of each characteristics in Table 11.1 and then determine the most suitable material to be used. Give a reason for your choice.

Type ofmaterial

Density(Kg/m -3)

Number of studs x Area of 1 stud

Expansion effect

Ability to stretch

P 820 6 x 30 cm2 Low GoodQ 700 8 x 30 cm2 Low GoodR 720 5 x 30 cm2 Medium AverageS 750 4 x 30 cm2 High PoorT 880 3 x 30 cm2 High Poor

Jawapan

Characteristic ReasonsLow density Small mass/lightMany/fewer/very few studs Gives extra/higher gripExpansion effect is low Always fits/Does not loosen when hot.Ability to stretch is good Less stress on the feet/Can be pushed in all directions/

Can walk on uneven surface.The most suitable material is Q Because it has a low density,many studs,low expansion effect and

good ability to stretch.

98. Table 12.2 shows the characteristics of five radioisotopes P, Q, R, S and T. As a factory engineer, you are required to determine the most suitable radioisotope that can be used by the system to ensure the volume of guava juice is uniform.Study the characteristics of all 5 radioisotopes and explain the suitability of the aspects.Determine the most suitable radioisotope and give the reason for your choice.

RadioisotopeRadioisotop Half life

Separuh hayatTypes of rayJenis sinar

State of matterKeadaan jirim

Ionising powerKuasa pengionan

P 7 hours alfa solid highQ 10 days beta liquid moderateR 100 days gamma solid lowS 10 years gamma liquid highT 30 years beta solid low

Jawapan

99. Yo

u are assigned to investigate the design for the location to keep the boats andthe characteristics of the retaining wall as shown in Diagram 12.2 based on the following aspects:

- the location to keep the boat- material used for the retaining wall- the height of retaining wall- size of slit

Explain the suitability of the location and the characteristics of the retaining wall and determine the most suitable design to keep the boat safely.

Characteristics ExplanationHas a long half-life Can be used for a long time hence save cost Emits beta Can penetrate box and liquid and is less

dangerous than gammaSolid form Easy to handle and contain.Low ionising power Does not change the state and taste of juice.Radioisotope T It has long half life, emits beta, in solid form and has low ionising power.

JawapanCharacteristic Reasons

Bay Wave is calmerConcrete retaining wall Stronger/ / lastingHigh wall Prevent high waveSmaller opening/aperture / slit ofretaining wall

Diffraction obvious //low wave energy

Choose P At bay, concrete retaining wall , high wall and smaller slit

100.Diagram 11.4 shows five designs of ‘Newton’s Cradle’, P, Q, R, S and T, with different specifications. You are required to determine the most suitable design to make the ball at the end swings up to higher level and at bigger speed. Study all the five designs from the following aspects:

− The arrangement of the balls − The type of material used to make the balls− the number of string used to hang the balls − the position of the ball to start the oscillation

JawapanCharacteristic Reasons

The balls touch each other This will reduce losses of energy which will reduce the speed of theballs

The type of material used to make theballs is steel

Steel balls are hard and produce highly elastic collision. Energy caneasily propagates through the intermediate balls.

Two strings used to hang each ball This string arrangement restricts the balls’ movements to the same plane. the position of the ball to start the oscillation

High position of the ball High potential energy and will change to high kinetic energy. The last end ball will swing at bigger speed.

The most suitable design is Q because the ball s touch each other, made from steel, use two strings attached to each ball and the initial position of the ball is high