1.1. Four students and their teacher do an experiment to measure the speed of sound in air.

The teacher stands at a distance and fires a starting pistol into the air.

The students see the flash when the pistol is fired.

They measure the time from when they see the flash to when they hear the bang.

A student drew a diagram of the arrangement as shown in Figure 7.

Figure 7

The students obtained a value of 240 m/s for the speed of sound.

The accepted value, in a science data book, is 343 m/s.

i) Calculate the difference between the students’ value and the accepted value as a percentage of the accepted value.

percentage difference = ............................................... %[2]

ii) When the distance was 100m, the students measured the following times:

Explain why their times vary so much.

[2]

iii) Explain one way the students might improve this experiment.

[2]

1.2. Figure 8 represents a sound wave coming from a loudspeaker and shows the effects on particles of the air at one instant in time.

Figure 8

i) Draw and label a distance of one wavelength in Figure 8.

[1]

ii) Describe the motion of the particles as the wave travels through the air.

[2]