AJC 2010 JC2 H2 Physics Prelim P3 QP

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9646/03/AJC2010Prelim [Turn Over

1

2010 JC2 Preliminary Examination

PHYSICS 9646/03Higher 2Paper 3 Longer Structured Questions Friday 17 September 2010

2 hours

Candidates answer on the Question Paper.No Additional Materials are required.

READ THESE INSTRUCTIONS FIRST

Write your name, register number and PDG on the spaces provided above.Write in dark blue or black pen on both sides of the paper.You may use a soft pencil for any diagrams, graphs or rough working.Do not use staples, paper clips, highlighters, glue or correction fluid.

Section AAnswer all questions.

Section BAnswer any two questions.

It is recommended that you spend about one hour on each section.

At the end of the examination, fasten all your work securely together.The number of marks is given in brackets [ ] at the end of eachquestion or part question.

For Examiner’s Use

1

2

3

4

5

67

Deduction

Total

ANDERSON JUNIOR COLLEGE

Candidate Name

PDG

( )

This question paper consists of 20 printed pages.



9646/03/AJC2010Prelim

2

Data

speed of light in free space, c = 3.00 x 108 m s-1

permeability of free space, μ 0 = 4π x 10-7 H m-1

permittivity of free space, ε 0 = 8.85 x 10-12 F m-1

(1/(36π)) x 10-9 F m-1

elementary charge, e = 1.60 x 10-19 C

the Planck constant, h = 6.63 x 10-34J s

unified atomic mass constant, u = 1.66 x 10-27 kg

rest mass of electron, m e = 9.11 x 10-31 kg

rest mass of proton, m p = 1.67 x 10-27 kg

molar gas constant, R = 8.31 J K-1 mol-1

the Avogadro constant, N A = 6.02 x 1023 mol-1

the Boltzmann constant, k = 1.38 x 10-23 J K-1

gravitational constant, G = 6.67 x 10-11 N m2 kg-2

acceleration of free fall, g = 9.81 m s-2




3

Formulae

uniformly accelerated motion, s = ut + ½ at 2

v 2 = u 2 + 2as

work done on/by a gas, W = p ΔV

hydrostatic pressure, p = ρ gh

gravitational potential, -=Gm

r φ

displacement of particle in s.h.m., x = x 0 sin ω t

velocity of particle in s.h.m., v = v 0 cos ω t

22

0 x x −±= ω

mean kinetic energy of a molecule of an ideal gasE =

2

3KT

resistors in series, R = R 1 + R 2 + …

resistors in parallel, 1/R = 1/R 1 + 1/R 2 + …

electric potential,

r 4

Q = V

0 πε

alternating current/voltage, x = x 0 sin ω t

transmission coefficient, T ∝ exp (-2kd )

where k =( )2

28

h

E U m −π

radioactive decay, x = x 0exp (- λ t )

decay constant,

12

0 . 6 9 3=

t λ




4

Section A

Answer all questions in this section.

1 (a) State Newton’s first law of motion and show it leads to the concept of force.

(b) A transport plane is to take off from a level landing field with two gliders in tow, one behindthe other as shown in Fig.1.1. Each glider has a mass of 1200 kg, and the friction force or

drag on each may be assumed to be constant and equal to 2000 N. The tension in thecable between the transport plane and the first glider is not to exceed 10 000 N.

(i) Determine the maximum acceleration acquired by the gliders.

maximum acceleration = ……….………… m s-2 [2]

(ii) If a velocity of 40 m s-1 is required for take off, calculate the minimum length of

runway required.

minimum length = ………………………… m [2]

Fig. 1.1

transport plane

glider glider

runway

[2]




5

(iii) Explain how the minimum length of runway will vary if only one glider is towed.

2 (a) A mass of 170 g oscillates with simple harmonic motion. Fig. 2.1 shows the variation withtime t of the displacement y of the mass.

(i) Use information from Fig. 2.1 to explain why the graph suggests that the oscillationsare undamped

(ii) On Fig. 2.2, draw a graph showing the variation with displacement y of the potentialenergy E p of the mass. [3]

[2]

Fig. 2.1

[1]

E p / mJ

y / cm1.0 2.0 3.0-3.0 -2.0 -1.0 0

Fig. 2.2




6

(b) Two charged points A and B are separated by a distance of 30.0 cm, as shown in Fig. 2.3.

The variation with distance x from A along AB of the potential V is shown in Fig. 2.4.

A test charge is moved along the line AB from x = 5.0 cm to x = 27 cm.

(i) Describe and explain the variation with distance x of the force acting on the testcharge.

(ii) State the value of x at which the force on the test charge is maximum.

x = ……….………… cm [1]

Fig. 2.3

[3]

Fig. 2.4




7

3 (a) A simple current balance is shown in Fig. 3.1.

`

A solenoid is connected to a horizontal rectangular copper loop PQRS, such that the samecurrent can pass through them. The loop is pivoted on two knife-edges X and Y and a riderof mass 2.0 g is placed on PQ. Electrical connections are made through the knife-edges.

Fig. 3.2 shows how the magnetic flux density B varies along the length of the solenoid.

When SR is at the centre of the solenoid and a current I m is passed through the loop, XYneeds to be at a quarter length of PS from PQ to balance the loop. When SR is at the end ofthe solenoid and a current I e is passed through the loop, XY needs to be shifted to midwayof the loop in order to regain its balance.

(i) Define the magnetic flux density .

(ii) Indicate on Fig. 3.1 the flow of the current through the solenoid. Label it I s. Explainhow you have obtained your answer.

[1]

[2]

Fig. 3.1

solenoid

X

Y

RS

Q

P

rider of 2.0 g

I m or I e

current into loop

current outof loop

120

Fig. 3.2

B / mT

end ofsolenoid end ofsolenoidcentre ofsolenoid

6080

100

2040




8

(iii) Find the ratio of I m to I e.

ratio = ………………………. [3]

(b) Fig. 3.3 shows a rectangular coil placed at the centre of the solenoid with its planeperpendicular to the axis of the solenoid

The solenoid has a cross-sectional area of 0.0050 m2 and length 50 cm, having 400 turns.The rectangular coil has 8 turns with dimensions of 0.010 m by 0.020 m. The ends of the

coil are connected to a cathode ray oscilloscope.

An alternating current of 50 Hz is passed through the solenoid. Its variation with time is asshown in Fig. 3.4.

(i) Explain why an e.m.f will be induced in the coil.

to oscilloscope

coilsolenoid

1.5

-1.5

Time / ms

Current / A

4020 3010

[2]

Fig. 3.3

Fig. 3.4




9

(ii) If magnetic flux density of solenoid, B = μ 0 n I ;

where μ 0 is the permeability of free space;n is the number of turns per unit length of solenoid; I is the current through the solenoid,

calculate the e.m.f induced in the coil.

induced e.m.f = ………………………. V [3]

(iii) Sketch a graph showing how the induced e.m.f in the coil varies with time over two

cycle of current change. [2]

4 (a) The photoelectric experiment provided the first evidence for the particulate nature of light.Describe one observation from the photoelectric experiment and explain how it providesevidence for the particulate nature of electromagnetic radiation.

(b) An experiment where two metal plates X and Y are contained in an evacuated containerand are connected in a circuit was conducted as shown in Fig. 4.1. Curve E in Fig. 4.2shows the current through the microammeter as a function of p.d. applied across XY whenincident light falls on plate X.

Time / ms

Induced e.m.f / mV

4020 3010

[2]




10

(i) The work function energy of metal X is 1.3 eV and the wavelength of the incident lightis 550 nm. Determine the value of V 1 in Fig. 4.2.

Value of V 1 = ………………………… V [2]

(ii) State the position of the sliding contact O to give the part pq shown on curve E inFig. 4.2. Explain your answer.

[2]

Fig. 4.2

I / μA

p.d. / V

Curve E

Curve F

V1V2

p q

Fig. 4.1

A B C

X Y

Monochromatic incident light

V

μA

O




11

(iii) The experiment in Fig. 4.1 was changed to obtain the curve F in Fig. 4.2. State and

explain the change(s) made to the experiment to produce the curve F.

(c) Another experiment was planned to investigate the properties of semiconductors. Discussqualitatively the origin of the depletion region at the p-n junction and use this to explain howa p-n junction can act as a rectifier.

[2]

[3]




12

Section B

Answer two questions in this section.

5 a (i) Define linear momentum.

(ii) State Newton’s second law.

(iii) Use your answer in (i) and (ii) to show that F = m a where F is the force, m is the massand a is the acceleration.

[1]

(iv) State the principle of conservation of momentum.

(b) A firework of mass 0.30 kg is launched with an initial velocity v of 8.0 m s-1 at an angle of 60°

to the ground, which is horizontal. Fig. 5.1 shows the path of the firework from the point ofprojection O to the point of maximum height P.

[1]

[1]

[1]

groundO

Fig. 5.1

60°

P

v




13

At the instant when the firework is at P, an internal explosion separates it into two parts, Aand B. The mass of A is 0.2 kg and the mass of B is 0.1 kg. Immediately after theexplosion, part A is momentarily at rest and part B moves horizontally. Parts A and B thenmove on different paths and strike the ground. It is assumed that all effects of airresistance are negligible for the whole process.

(i) Calculate the momentum of the firework just before the explosion.

momentum = …………………………kg m s-1 [1]

(ii) Calculate the momentum of part B immediately after the explosion.

momentum = …………………………kg m s-1 [2]

(iii) Determine the additional kinetic energy supplied to parts A and B by the explosion.

Additional kinetic energy = ………………………… J [3]

(iv) Sketch on Fig. 5.1 the paths followed by parts A and B after the explosion. Labelthese paths as A and B clearly. [2]

(v) Calculate the time for part A to reach the ground.

time = ………………………… s [1]




14

(vi) Suggest and explain whether part B will take lesser, same or greater time to reachthe ground than your answer in (b)(v).

(vii) Determine the distance apart of parts A and B when they strike the ground.

Distance apart = ………………………… m [1]

(c) (i) If the firework in part (b) fails to explode and air resistance is not negligible, will thefirework reach a point lower, same or higher than point P? Explain.

(ii) Sketch on Fig. 5.2 the path of the firework when it fails to explode where1. air resistance is negligible. Label the path as R.

2. air resistance is not negligible. Label the path as S.[2]

[2]

ground

Fig. 5.2

60°

P

v

[2]




15

6 (a) (i) Explain the meaning of the term diffraction .

(ii) A ripple tank experiment is used to observe the appearance of plane water wavespassing through gaps. Sketch on Fig. 6.1 and Fig. 6.2 the diffraction of the waterwaves. [2]

(iii) A band is practising in the band room down the corridor with the door slightly ajar.Explain why a student walking along the corridor can hear the band but cannot see the

band.

(b) A student was standing 5.50 m away a loudspeaker S1 placed at point X. The loudspeakerS1 is transmitting with a power output of 20.0 W.

(i) Assuming the loudspeaker S1 is radiating uniformly in all directions and sound wavesfrom the loudspeaker strikes the surface of the student’s ear perpendicularly, calculate

the power intercepted by the student’s ear with an effective area of 2.0 × 10 –3 m2.

power = ………………… W [2]

[2]

[1]

Fig. 6.2

Fig. 6.1




16

(ii) The actual power received by the student’s ear is 4.36 × 10 –2 W. Suggest why theactual power received is greater than that calculated in (b)(i).

(c) A second loudspeaker S2 placed at point Y is 1.2 m from loudspeaker S1 as shown inFig. 6.3. The sound waves from the two loudspeakers have frequency 2.75 kHz and speed330 m s –1.

(i) Explain what is meant by the principle of superposition with reference to the soundwaves emitted from the two loudspeakers.

(ii) Show that the wavelength of the sound waves is 0.12 m. [1]

(iii) The loudspeaker S1 emits a signal that arrives at point A with intensity I and the

loudspeaker S2 emits a signal that arrives at point A with intensity 2 I . The studentnow stands on the centre line at point A and hears a sound of maximum intensity.As the student moves from point A to point B, the intensity varies between maximumand minimum values. At point B, the distance S1B is 3.82 m and S2B is 4.12 m.Determine the number of high intensity regions that are found between points A andB. Do not include the maximum at point A.

number of high intensity regions = ……………… [2]

[1]

[2]

1.2 m

X

Fig. 6.3Y

3.7 m

A

B

S2

S1




17

(iv) State one condition that allowed the student to be able to hear the maxima andminima intensity pattern.

(v) Determine the intensity of the sound at point B in terms of I .

intensity = ………………….. [2]

(vi) Now, the two loudspeakers are placed closer together along the line joining X and Y.Without any calculations, state the difference that would be detected by the studentas she walks from point B back to point A.

(d) Keeping the same frequency, the two loudspeakers S1 and S2 are now placed facing each

other, at a distance d apart as seen in Fig. 6.4. A microphone is placed at Z, midwaybetween loudspeakers S1 and S2.

(i) Explain why the microphone detects maximum signal at point Z.

(ii) As the microphone moves from S1, a position of maximum intensity, to S2, also aposition of maximum intensity, along a line joining S1S2, it detects 6 positions ofminimum intensity. Determine the value of d .

distance d = ……………….. m [2]

[1]

[1]

[1]

d

S1 S2

Fig. 6.4

Z




18

7 (a) (i) Define, in the context of an electrical circuit, the following,

Coulomb

Joule

Watt

(ii) Based on your answers in (a)(i), hence, show the units for potential difference in terms

of SI base units. [2]

(b) A car headlamp is marked 12 V, 72 W.

(i) Calculate the working resistance of the car headlamp.

working resistance = ……………………… Ω [2]

(ii) The lamp in (b)(i) is connected to a battery of e.m.f. of 12 V with an internal resistance

of 0.20 Ω as shown in Fig 7.1.

[1]

[1]

[1]

12 V

0.20 Ω carheadlamp

Fig 7.1




19

The car headlamp is switched on for a 20 minute journey.

1. Using your answer in (b)(i), calculate the current in the lamp.

current = ……………………... A [2]

2. the charge which passes through the lamp during the journey,

charge = ……………………… C [1]

3. the energy supplied to the lamp during the journey.

energy = ……………………… kJ [2]

(c) Two of the headlamps referred to in (b) are connected into the circuit shown in Fig 7.2, inwhich one source of e.m.f. (generator of the car) is placed in parallel with the car battery andthe two lamps. Both lamps are on and are working normally.

The battery has an e.m.f. of 12.0 V and an internal resistance of 0.20 Ω. The generator hasan e.m.f. of 15.0 V and negligible internal resistance. The generator is in series with avariable resistor R .

+

–

15.0 Vgenerator

R

Fig 7.2

12 V

0.20 Ω



20

(i) The value of R is adjusted so that there is no current in the battery when the lamps areon. Calculate

1. the current in the generator,

current = …………………… A [2]

2. the value of the resistance of R .

resistance = ………………………… Ω [2]

(ii) Calculate the current in the battery when both lamps are switched off, the value of R remaining the same as in (i).

current = ……………………… A [2]

(d) Suggest two advantages which the circuit, as shown in Fig 7.2, has over a single powersource.

[2]

AJC 2010 JC2 H2 Physics Prelim P3 QP

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