You will complete 12 Specified Practical Activities if you are studying GCSE Physics. You could be asked questions about the apparatus, methods, safety precautions, results, analysis and evaluation of these experiments.
Waves can travel across the surface of water. Their speed depends upon the depth of the water.
Water is placed into a plastic tray. The depth of water is measured.
Some pupils time how long it takes a wave to travel 4 lengths of the tray.
They repeat the timing for each depth of water.
Here are the results obtained from their experiment.
|Depth of water (cm)||Time taken 1 (s)||Time taken 2 (s)||Mean time (s)||Wave speed (cm/s)|
a) Complete the table to show the missing mean time at a water depth of 3.0 cm. [1 mark]
b) i) Plot the data on some graph paper and draw a suitable line to show how the wave speed depends upon the depth of water. [3 marks]
ii) Describe how the wave speed changes with an increasing depth of water. [2 marks]
iii) Use the graph to find the wave speed for water that has a depth of 2.5 cm. [1 mark]
c) Use data from the table and recall an equation to calculate the length of the plastic tray. [3 marks]
Question courtesy of Eduqas.
a) 1.3 seconds 
b) i) Scales on both axes with more than ½ of the grid used . All Points correct, no tolerance allowed . A best fit curved line drawn passing through (0, 0) .
ii) Wave speed increases  at a decreasing rate 
iii) 65 ± 1 cm/s 
c) Any row of data used
eg Distance = 30 × 3.0 = 90 cm 
Tray length = 90 ÷ 4 lengths 
= 22.5 cm 
It is possible to measure the speed of sound using two microphones connected to a computer, with a bell in a school laboratory.
The computer must listen for the sound wave using two microphones. The timing process is started and then stopped when the sound reaches each microphone in turn.
a) Why is it better to use a computer rather than a stop clock to measure time in this experiment? [1 mark]
b) If the distance between the microphones is 3.4 m and the time taken for the sound wave travel is 0.01 s, calculate the speed of sound in air by using the formula given. [2 marks]
c) What type of wave is a sound wave? [1 mark]
d) The speed of sound through a solid is much bigger than through air. Explain why this is so. [1 mark]
This question has been written by a Bitesize consultant as a suggestion to the type of questions that may appear in an exam paper.
a) The time interval is so small, less than a person's reaction time, meaning that a stop clock would be unable to measure small times with any accuracy. 
b) Speed = 3.4 ÷ 0.01 
= 340 m/s 
c) Longitudinal 
d) The value would be higher. This is because the particles are closer together and the energy passes from one to the other much more quickly and easily.