Physics Fr4 Chapter 1

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PHYSICS SPM

FORM 4 STUDY NOTES

NAME : _________________________________ CLASS : FOUR SCHOOL : KOTA KINABALU HIGH SCHOOL

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Physics SPM SPM Examination Format

1. Paper 1

- Objective - 50 questions ( Answer ALL ) - Time : 1 hour 15 minutes - Total marks : 50

2. Paper 2

- Subjective - Time : 2 hours 30 minutes - Total marks : 100 - Section A : - 8 structure questions - Answer ALL - 60 marks - Section B : - 2 essay questions

- Choose ONE - 20 marks

- Section C : - 2 essay questions - Choose ONE - 20 marks 3. Paper 3

- Subjective - Time : 1 hour 30 minutes - Total marks : 40

- Section A : - 2 structure questions - Answer ALL - 28 marks - Section B : - 2 essay questions - Choose ONE - 12 marks

4. Paper 4

- Experiment reports ( PEKA ) - At least 4 reports

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CHAPTER 1 INTRODUCTION TO PHYSICS

1. A physical Quantity is a quantity that can be measured. Example: length, temperature and volume.

Non Physical Quantity is a quantity that cannot be measured. Example: Beauty, loyalty, feelings. 2. Physical quantity is expressed as a numerical value in a particular unit of measurement. Example:

3. The unit of measurement always follows the SI unit (The international system of units). 4. The base quantity is a physical quantity that cannot be defined in terms of other physical quantities. 5. There are 5 base quantities.

Base quantities SI units

Name Symbol Name Symbol

Length L Metre M

Mass M Kilogram Kg

Time T Second S

Temperature T Kelvin K

Current I ampere A

6. A derived quantity is a combination of various base quantities.

Example: (a) Density =mass/volume =mass/(length)3 Unit = kg/m3

(b) Volume = length X length X Length Unit = m3 7. Very large or very small numbers are expressed in 2 methods.

(a) Standard form / Scientific notation: A x 10 n, 1 ≤ a ≤ 10. Example : (i) 24300 m = 2.43 X 104 m (ii) 0.0071 s = 7.1 X 10-3 s (iii) 25 km = 2.5 X 104 m

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(b) Prefixes

Prefix Symbol Value

Tera T 1012

Giga G 109

Mega M 106

Kilo K 103

Deci D 10-1

Centi C 10-2

Milli M 10-3

Micro Μ 10-6

Nano N 10-9

Pico P 10-12

Example : (a) 95.7 M Hz = 9.57 X 106 Hz (b) 2.15 cm = 2.15 X10-2 m (c) 0.073 T kg = 7.3 X 10-2 kg 8. Conversion of units (a) 21 cm 2 = 2 X 10-4 m 2 (b) 1.05 g cm -3 = 1.05 X 103 kg m -3 (c) 0.02 m 2 = 2 X 106 mm 2 (d) 3.86 m s = 3.86 X 10-3 s (e) 6.37 km = 6.37 X 103 m (f) 25 h cm -3 = 9.0 X 1010 s m -3

9. Calculation

(a) 2

5

1013.2

105.2

= 2 X 106

(b) 25 - 2

104.33 5 = 2 X 106

(c) 245 + 1510523 = 2 X 106

(d) Sin θ = 0.3578 ; θ = 2 X 106 (e) Tan θ = 1.5 ; θ = 2 X 106

(f) 2 + kos 20º - 3 45 = 2 X 106

(g) 2

4

1

3 3508

5 = 2 X 106

(h) Kos '2556 = 2 X 106

(i)

7

321085.2

49

35 8 = 2 X 106

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10. A scalar quantity is a physical quantity which has magnitude only. Example : time, temperature, distance, speed, mass, volume.

11. A vector quantity is a physical quantity which has both magnitude and direction. Example : force,displacement, weight, velocity, momentum, acceleration . * force and resultant force * distance and displacement

Error 1. Error is the difference between the actual value of a quantity and the value obtained in

measurement. 2. There are 2 main types of error

(a) Systematic errors.

(i) The sources of the systematic errors : (1) zero error – the pointer of the instrument does not point to zero when

Nothing to measure, not in use and the true reading is Zero. (2) Incorrect calibration of the measuring instrument. (3) Reaction time for observer.

(ii) The readings may look the same but not the real reading. All readings always smaller or

larger than the true value.

(iii) cannot be eliminated by repeating the measurements and averaging out the results; Only can be eliminated of the measuring instruments are calibrated frequently.

(iv) Zero error can be corrected by compensating the readings by substract the zero error. (b) Random errors. (i) The sources of random errors :

(1) Random errors such as changes in wind, temperature and miscount, taking wrong reading.

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(2) Wrong estimating of measurement. (3) Personal errors such as wrong calculation, human limitation of sight and touch.

(4) Parallax error - the observer’s eye and the pointer are not in a line perpenticular to the plane of the scale.

- To avoid parallax error

(a) The position of eye must be directly upright in front of the scale of an instrument when taking measurements.

(b) To overcome instruments with a scale and pointer eg. Ammeter, often have a mirror behind the pointer.

(ii) random errors can be minimized by repeating the measurement several

times and taking the average of the readings.

Consistency 1. Consistency ( Precision ) is the degree of a measuring instrument to record same physical quantity

readings for each measurement by the same method, same tools.

2. Relative deviation =

X 100%

3. Deviation is the difference between a measured value and its average value. 4. Small relative deviation means high consistency.

Example : The mass of an object was measured 5 times and the results are 35.1 g, 35.0 g, 35.2 g, 35.1 g and 35.5 g. Find relative deviation.

Accuracy 1. Accuracy is the degree of the measuring instrument to record actual value without error.

2. Relative error =

X 100%

Reading/g Deviation= Іreading-average

readingІ

35.0 0.2 Average deviation =

35.1 0.1 = 0.14

35.1 0.1 Realtive deviation =

X 100%

35.2 0 = 0.39%

35.5 0.3

Total 175.9 0.7

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3. Error is the degree of defference between the measured value and the actual / true value. 4. Small relative error means increase in accuracy.

Example : The length of the object was measured 5 times and the values are 2.5 cm, 2.4 cm, 2.5 cm, 2.3 cm and 2.6 cm. However, the actual value of the object is 2.4 cm. Find the relative error.

Sensivity 1. Sensitivity is the degree of a measurement to record small changes in its readings. 2. The smaller division of the scale for the measuring instrument, the higher sensitivity of the

measuring instrument.

Measuring instruments (a) Ruler (i) accuracy = 0.1 cm = 1 mm (ii) precautions to be taken when using a ruler

(1) avoid parallax errors (2) avoid zero and end errors

(b) Stop watch (i) to measure time and the accuracy depends on the scale of the stop watch. (ii) two types of stop watch : (a) analogue stop watch (b) digital stop watch (c) Thermometer (i) Accuracy = 0.5 ºC (ii) Range of temperature = -10 ºC until 110 ºC

Reading/cm Error = Іreading-average readingІ

2.3 0.2 Average error =

2.4 0.1 = 0.08

2.5 0 Realtive deviation =

X 100%

2.5 0 = 3.2%

2.6 0.1

Total 12.3 Mean 0.4

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(iii) Sensitivity for thermometer increases by using (1) diameter capillary tube (2) Thin-walled bulb (3) Mercury - sensitive to temperature changes, freezing point 39C

- expands and contracts uniformly with temperature (4) Alcohol - freezing point -115C, expand uniformly,

(d) Vernier Calipers (i) used to measure inner diameter, outer diameter and depth.

(ii) There are two steel bar scales, one sliding over the other. (1) The main scale is graduated in intervals of 0.1 cm from 0 cm to 12 cm. (2) The sliding vernier scale has a scale on which 10 divisions are equal to 9 small

divisions on the main scale.

0 cm 1 cm Main scale Vernier scale 0 5 10

(iii) The reading of the vernier caliper : answer in 2 decimal points and using unit cm.

(1) 5 cm 5.17 cm (2)10 cm 10.22 cm 0 0 (iv) If the vernier caliper with a zero error, the correct reading = observed reading – zero error. (v) Zero error

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(1) No zero error when the “0” mark of the main scale and vernier scale is exactly in line.

0 1 cm 0 10 Zero error = 0.00 cm

(2) Positive zero error 0 0 Zero error = 0.03 cm (3) Negative zero error

0

0 Zero error = -0.05 cm Example : Find the correct reading of the object. 0 8 Zero error = -0.05 cm

Observed reading = 8.14 cm Correct reading = 8.19 cm

0 0

(e) Micrometer screw gauge

(i) to measure small length until 0.01 mm or 0.001 cm ( 2.5 cm ) (ii) consist 2 scale

(1) main scale marked on sleeve with the smallest division 0.5 mm

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(2) thimble scale marked on thimble is sub-divided into 50 divisions. When the thimble is rotated one complete turn ( 360º ), the gap between the anvil and spindle increase / decrease 0.5 mm.

(iii) One division in the thimble = 0.01 mm.

Hence, the accuracy for micrometer screw gauge = 0.005 mm.

(vi) The reading of the micrometer screw gauge : answer in 2 decimal points and using unit mm.

(1) (2)

(v) If the micrometer screw gauge with a zero error ; The correct reading = observed reading – zero error.

(vii) Zero error

(1) No zero error

The “0” mark on the thimble scale is exactly in line with the horizontal reference line.

Zero error = 0 mm (2) Positive zero error Zero error = 0.02 mm

0

5

45

5 0

5

18 5

15

0

0

0

0

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(3) Negative zero error

Zero error = 0.03 mm Example : Find the correct reading for the object. Zero error = 0.03 mm Observed reading = 14.35 mm Correct reading = 14.32 mm (f) Ammeter (i) to measure amount of current . (ii) SI unit : Ampere , A (iii) connect in series in an electrical circuit. (iv) symbol for ammeter : A and milliammeter : mA (v) accuracy depends on the smallest division of the scale of the meter.

(f) Voltmeter (i) to measure potential difference / Voltage .

0

0

0

14

35

mA

V

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(ii) SI unit : volt , V (iii) connect in parellel in an electrical circuit. (iv) symbol for voltmeter :V

(v) accuracy depends on the smallest division of the scale of the meter. Tabulating Data Example : The temperature of the tap water in the beaker are recorded for every 5 minutes.

Time,t/s Temperature,T /C

1 2 ave

5 35.5 35.5 35.5

10 40.0 41.5 40.8

15 56.5 55.5 56.0

20 62.0 62.5 62.3

25 70.5 71.5 71.0

30 80.5 79.0 79.8

First column Second column 1. Title for each column consists of nameof the quantity, symbol and unit. 2. First column must be manupulated variable. 3. Second column must be responding variable. 4. Each column must has the same decimal places.

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Graph drawing

Graph against t 1. Add a title to the graph and label the axes. X-axis normally for manupulated variable and Y-axis for

responding variable. 2. Scale of graph - use even scale; 1 cm : 1, 2, 5, 10 unit - All axes should start from origin, ( 0, 0 ) - The scales for the two axes need not be similar 3. Plotting the coordinate : mark with a cross “ X ” 4. Use one-page graph paper to plot the graph 5. Use pencil to draw the graph including title. 6. Line / Curve of the graph - the number of points above and below the straight line / curve must be balance - pass through as many points as possible - smooth Analysing graphs 1. Types of graph

(a) Linear graph (i) (ii) (iii) Y = mx + c (b) Curve

(i) (ii) (iii)

Y =ax2+bx +c

y

x

y

x

y

x

y

x

y

x

y

x

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2. Formula of linear graph : y = m x + c

m = gradient = x

y

( m>0 - positive gradient ; m<0 - negative gradient )

c = y-intercept

3. Gradient of a curve is not a constant Gradient increases with x Gradient decreaces with x 4. Extrapolation of graph y x

(i) Extrapolation of a graph is a technique of estimating the value of a quantity falling out of

the range of measured values. (ii) y – intercept ( x = 0 ) and x – intercept ( y = 0 ) * Saiz of the graph ( first until last point ) = 8 cm x 10 cm ** Saiz of the trangle ( draw with dotted line ) to find gradient = 2 cm x 6 cm

y

x

y

x

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Exercise

Time, t / s Temperature, / ºC

1.7 2.0

2.2 2.8

2.9 3.6

3.5 4.4

4.0 5.0

1. (a) State (i) manipulated variable : time

(ii) responding variable : temperature

(b) Plot graph against t.

(c) Find the gradient of the graph.

m =

= 3.0/2.3 cs-1= 1.3 cs-1

(d) State the equation of the graph.

= 1.3 t

(e) State the relationship between and t.

is directly proportional with t

(f) Find the value of when t = 1 s.

Mass, m /g Length, l / cm

5 16.0

10 20.5

15 24.5

20 28.5

25 33.0

30 37.5

2. (a) State (i) manipulated variable : mass

(ii) responding variable : length

(b) Plot graph l against m.

(c) Find the gradient of the graph. (d) State the equation of the graph. (e) State the relationship between l and m. _______________________________________________________________________ (f) Find the value of l when m = 18 g.

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Current, I / A Temperature, / ºC

2 75.1

4 38.2

6 22.0

8 17.5

10 16.0

12 14.5

14 13.8

3. (a) State (i) manipulated variable : current

(ii) responding variable : temperature

(b) Plot graph against I.

(c) State the relationship between I and . _______________________________________________________________________

(d) Find the value of I when = 20.0 ºC. 4. Measure the height for each of the metal block below and tabulate your data.

m = 10 g m = 15 g m = 20 g m = 25 g m = 30 g

(a) State (i) manipulated variable : mass

(ii) responding variable : height, length

(b) Plot graph h against m.

(c) Find the gradient of the graph. (d) State the relationship between h and m. _______________________________________________________________________