Effects of Forces (Cambridge (CIE) IGCSE Physics)

Exam Questions

2 hours33 questions

1a2 marks

The class is investigating the behaviour of a spring, and then using the spring to determine the weight of an object.

The apparatus is shown in Fig. 3.1.

The stretched length $l$ of the spring, indicated in Fig. 3.1, is to be measured.

Describe two precautions that could be taken when measuring the length of the stationary spring, to ensure an accurate reading. You may draw a diagram.

How did you do?

1b1 mark

A student measures the length $l_{0}$ of the spring without any load.

$l_{0}$ = 2.1 cm

Various loads L are hung on the spring. The stretched length $l$ of the spring for each load is recorded in Table 3.1.

Table 3.1

L/N	$l$ /cm	e/cm
1.0	6.3
2.0	10.5
3.0	14.7

Calculate, and record in Table 3.1, the extension e of the spring for each load L. Use the equation $e = (l - l_{0})$

How did you do?

1c1 mark

The loads are removed and an object X is suspended from the spring.

The unstretched length $l_{x}$ of the spring on Fig 3.2 is 11.4 cm

Estimate the weight W_X of object X.

Explain how you obtained your answer.

W_X = ........................................................... N

How did you do?

1d1 mark

A student measures the weight of a different load using a similar method. He gives the weight as 4.532 N.

Explain why this is not a suitable number of significant figures for this experiment.

1e4 marks

(i) Another student suggests that e is directly proportional to L.

State whether the results support her suggestion.

Use values from the results in Table 3.1 to justify your statement.

[2]

(ii) The student wishes to plot a graph of L against e to test if the two quantities are directly proportional.

State how her graph line could show that e is directly proportional to L.

[2]

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2a1 mark

A student is determining the spring constant k of a spring by two methods.

Fig. 1.2 shows how the apparatus is used.

Method 1

On Fig. 1.1, measure the unstretched length $l_{0}$ of the spring, in mm.

$l_{0}$ = ................................................. mm

How did you do?

2b2 marks

Extended tier only

The student attaches the spring to the clamp as shown in Fig. 1.2.

He hangs a 300 g mass on the spring.

He measures the new length $l$ of the spring.

$l$ = 53 mm

(i) Calculate the extension e of the spring using the equation $e = l - l_{0}$ .

e = ................................................. mm [1]

(ii) Calculate a value for the spring constant k using the following equation:

$k = \frac{F}{e}$ ,

where F = 3.0 N.

k = ............................................ N/mm [1]

How did you do?

2c4 marks

Method 2

The student pulls the mass down a short distance and releases it so that it oscillates up and down. Fig. 1.3 shows the time t taken for 10 complete oscillations.

(i) Record the time t taken for 10 complete oscillations.

t = ........................................................ [1]

(ii)

1. Calculate the time T taken for one complete oscillation.

T = .............................................................

2. Calculate T².

T² = .............................................................

[2]

(iii)

Calculate the spring constant k using the following equation:

$k = \frac{0.040 m}{T^{2}}$ ,

where m = 0.300kg.

k = ............................................ N/mm [1]

How did you do?

2d2 marks

State and explain whether your two values for k are the same within the limits of experimental accuracy.

2e2 marks

A student states that repeating Method 1 with different masses would improve the reliability of the value obtained for k.

Suggest additional values for the mass m that you would use when repeating the experiment to improve the reliability.

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