Measurement: Physics Tingkatan 4 questions

Section A: objective questions

12 marks

Choose the best answer for each question.

Which of the following is a base quantity?

Velocity
Mass
Density
Force

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Mass is one of the seven base quantities. Velocity, density and force are derived quantities.

For the teacher: Remembering, low difficulty, standard 1.1.2

Textbook p. 6

What is the S.I. unit of electric current?

ampere
coulomb
volt
mole

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The base unit of electric current is the ampere (A). The coulomb is the unit of charge; the mole is the unit of amount of substance.

For the teacher: Remembering, low difficulty, standard 1.1.2

Textbook p. 6

Which of these is a vector quantity?

Speed
Distance
Displacement
Temperature

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Displacement has magnitude and direction. The other three have magnitude only.

For the teacher: Understanding, low difficulty, standard 1.1.4

Textbook p. 9

Force is given by F = ma. What is the unit of force in S.I. base units?

kg m s⁻¹
kg m² s⁻²
kg s⁻² m⁻¹
kg m s⁻²

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a has unit m s⁻², so F = kg × m s⁻² = kg m s⁻² (a newton).

For the teacher: Applying, medium difficulty, standard 1.1.3

Textbook p. 7

Acceleration a = v / t. What is its unit in S.I. base units?

m s⁻¹
m s⁻²
m² s⁻¹
kg m s⁻²

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v is in m s⁻¹, so a = (m s⁻¹) / s = m s⁻².

For the teacher: Applying, low difficulty, standard 1.1.3

Textbook p. 7

Diagram 1 shows a graph of y against x. What is the gradient of the graph?

Straight line through (0, 10), (5, 20), (10, 30) and (15, 40) — Diagram 1

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Gradient = (40 − 10) / (15 − 0) = 30 / 15 = 2.0.

For the teacher: Applying, medium difficulty, standard 1.2.2

Textbook p. 12

Diagram 2 shows three graphs of p against q. Which graph shows that p is inversely proportional to q?

Graph (a) a straight line through the origin, (b) a curve that does not touch either axis, (c) a straight line with a negative gradient — Diagram 2

(a)
(b)
(c)
None of them

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An inverse relationship gives a curve that does not touch either axis (graph b). Graph (a) is direct proportion; graph (c) is a linear decrease that cuts the axes.

For the teacher: Understanding, low difficulty, standard 1.2.1

Textbook p. 11

A graph of y against x is a straight line that passes through the origin. What does this show?

y is directly proportional to x
y is inversely proportional to x
y decreases as x increases
y is equal to a constant

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A straight line through the origin has the equation y = mx, so y is directly proportional to x.

For the teacher: Remembering, low difficulty, standard 1.2.1

Textbook p. 10

Diagram 3 shows a speed-time graph of a car. What is the distance travelled in 10 s?

Straight line from 0 m/s at 0 s to 20 m/s at 10 s — Diagram 3

20 m
50 m
100 m
200 m

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Distance = area under the graph = ½ × 10 s × 20 m s⁻¹ = 100 m.

For the teacher: Applying, medium difficulty, standard 1.2.2

Textbook p. 12

Reading a value from a graph beyond the range of the plotted data is called

interpolation
calibration
extrapolation
sketching

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Extending the line beyond the data to predict a value is extrapolation. Reading between plotted points is interpolation.

For the teacher: Understanding, low difficulty, standard 1.2.2

Textbook p. 12

A pendulum takes 36.0 s to make 20 complete oscillations. What is its period?

1.80 s
0.56 s
18.0 s
720 s

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T = 36.0 / 20 = 1.80 s.

For the teacher: Applying, low difficulty, standard 1.2.3

Textbook p. 15

Power P = (force × length) / time. What is the unit of P in S.I. base units?

kg m s⁻²
kg m² s⁻²
kg m s⁻³
kg m² s⁻³

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Force = kg m s⁻², times m gives kg m² s⁻², divided by s gives kg m² s⁻³ (the watt).

For the teacher: Analysing, high difficulty, standard 1.1.3

Textbook p. 7

Section B: structured questions

32 marks

Answer all questions. Show your working.

Physical quantities are either base quantities or derived quantities.

[3 marks] (a)State the S.I. unit and its symbol for each base quantity: (i) time, (ii) thermodynamic temperature, (iii) luminous intensity.

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Second, s1
Kelvin, K1
Candela, cd1

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[2 marks] (b)Pressure P = F / A. Derive the unit of pressure in S.I. base units.

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Unit of F = kg m s⁻², unit of A = m²1
P = kg m s⁻² / m² = kg m⁻¹ s⁻²1

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For the teacher: Remembering, low difficulty, standard 1.1.2

Textbook p. 6

A pupil's height is measured with a tape measure and the reading is 1.65 m.

[1 mark] (a)State the physical quantity that is measured.

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Length (height)1

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[2 marks] (b)State the S.I. unit of this quantity and its symbol.

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Metre [1]1
m [1]1

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[1 mark] (c)State the magnitude of the measurement.

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1.651

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For the teacher: Remembering, low difficulty, standard 1.1.1

Textbook p. 5

A driver wants to travel 240 km to Kuantan at a speed of 80 km h⁻¹. To arrive on time she increases her speed with an acceleration of 0.5 m s⁻².

[1 mark] (a)State the difference between a scalar quantity and a vector quantity.

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A scalar has magnitude only; a vector has magnitude and direction1

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[2 marks] (b)Name two scalar quantities in the passage.

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Distance1
Speed1

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[1 mark] (c)Which quantity in the passage is a vector?

DistanceSpeedTimeAcceleration

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Acceleration

For the teacher: Understanding, low difficulty, standard 1.1.4

Textbook p. 9

Diagram 4 shows a graph of the force F applied to another spring against its extension x.

Straight line through the origin, passing through (2 cm, 1.0 N) and (10 cm, 5.0 N) — Diagram 4

[1 mark] (a)State the relationship between F and x.

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F is directly proportional to x1

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[2 marks] (b)Calculate the gradient of the graph in N m⁻¹.

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Gradient = (5.0 − 1.0) / (10 − 2) [1]1
= 0.50 N cm⁻¹ = 50 N m⁻¹ [1]1

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[2 marks] (c)Calculate the work done to stretch the spring by 8.0 cm. (Work = area under the graph.)

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F at 8.0 cm = 0.50 × 8.0 = 4.0 N [1]1
W = ½ × 4.0 × 0.080 = 0.16 J [1]1

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[1 mark] (d)Predict the extension when F = 7.0 N.

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x = 7.0 / 0.50 = 14 cm1

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For the teacher: Analysing, medium difficulty, standard 1.2.2

Textbook p. 13

Diagram 5 shows the speed v of a car against time t. The car already has a speed when timing starts.

Straight line from 10 m/s at 0 s to 40 m/s at 20 s — Diagram 5

[1 mark] (a)State the y-intercept and what it represents.

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10 m s⁻¹, the speed of the car at t = 0 (initial speed)1

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[2 marks] (b)Calculate the gradient and state what it represents.

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Gradient = (40 − 10) / 20 = 1.5 m s⁻² [1]1
It is the acceleration of the car [1]1

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[2 marks] (c)Calculate the distance travelled in the first 20 s, using the area under the graph.

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Area = (10 × 20) + (½ × 20 × 30) [1]1
= 200 + 300 = 500 m [1]1

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For the teacher: Analysing, high difficulty, standard 1.2.2

Textbook p. 12

A pupil investigates a simple pendulum. For a pendulum of fixed length, 20 complete oscillations take 32.0 s. Use g = 10 m s⁻² and π = 3.14.

[1 mark] (a)Calculate the period T.

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T = 32.0 / 20 = 1.60 s1

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[1 mark] (b)Why is the time for 20 oscillations measured, rather than one?

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Reduces the error caused by reaction time / one oscillation is too short to time accurately1

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[2 marks] (c)The length l is given by l = (g / 4π²) T². Calculate l.

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l = (10 / (4 × 3.14²)) × 1.60² [1]1
= 0.65 m [1]1

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[1 mark] (d)State one precaution to increase the accuracy of the results.

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Any 1 points

Displace the bob through a small angle (less than 10°)1
Keep the eye perpendicular to the scale / start the watch when the bob passes the centre1
Repeat and take the average1

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For the teacher: Evaluating, medium difficulty, standard 1.2.3

Textbook p. 15

A pupil suspects that the period of a simple pendulum depends on the mass of the bob. Plan an investigation.

[2 marks] (a)State the manipulated variable and the responding variable.

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Manipulated variable: mass of the bob1
Responding variable: period of oscillation, T1

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[1 mark] (b)State one variable that must be kept constant.

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Any 1 points

Length of pendulum1
Angle of displacement1

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For the teacher: Creating, medium difficulty, standard 1.2.3

Textbook p. 14

Section A: objective questions

Question 1

Question 2

Question 3

Question 4

Question 5

Question 6

Question 7

Question 8

Question 9

Question 10

Question 11

Question 12

Section B: structured questions

Question 13

Question 14

Question 15

Question 16

Question 17

Question 18

Question 19