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GCSE Questions - Waves

Q12. The clock shown below uses a pendulum to keep time.

(a) The pendulum has a frequency of 0.80 Hz.

Calculate the periodic time of the pendulum.

T = 1/f

T = 1/0.80

T = 1.25 s

T = 1.3 s

The answer should be given to the same number of significant figures as the data provided (in this case 2 sig figs)

[2 marks]

(b) Ragnar investigated the factors affecting the oscillation of a pendulum. He set up a pendulum as shown in the diagram.

Ragnar investigated how many complete oscillations the pendulum made for different lengths of the pendulum and different masses of the pendulum bob. His results are shown in the table.

Length of the pendulum/mm
Mass of the pendulum bob/g
Number of complete oscillations made by the pendulum in 20 s
200
100
22
200
200
22
400
100
15
400
200
15
600
50
13
600
100
13

 

(i) State two conclusions that Ragnar should make from the results shown in his table.

Changing the mass of the bob has no effect on the period of the pendulum.

The period of the pendulum increases as the length of the pendulum is increased or you get less oscillations in a given time as the length of the pendulum is increased.

[2 marks]

(ii) He wants to be more certain that his conclusions are correct.

Suggest two ways in which the investigation could be improved.

Any two suitable improvements:

measure (the number of swings) over a wider range of (pendulum) lengths

measure (the number of swings) over a wider range of (bob) masses

measure the number of swings made over a greater period of time

repeat each measurement and calculate a mean/average number of oscillations (while discarding anomalous measurements)

measure the total number of swings and the fraction of swings made

start the swings at the same height

Just saying 'repeat measurements' was insufficient to get you a mark.

Saying 'use a computer / datalogger' to make a measurement of the number of oscillations also was considered insufficient as was using a stop clock with greater resolution.

[2 marks]

(Total 6 marks)