Physics (AS & A Level) · Oct / Nov 2020 · Paper 12 · Question 23

When sound travels through air, the air particles vibrate. A graph of displacement against time for a single air particle is shown. Which graph shows how the kinetic energy of the air particle varies with time?

1. Akinetic energy against time graph: starts at maximum at t=0, falls to zero at T/2, rises to maximum at T, falls to zero at 3T/2, rises to maximum at 2T
2. Bkinetic energy against time graph: starts at zero at t=0, rises to maximum at T/2, falls to zero at T, rises to maximum at 3T/2, falls to zero at 2T
3. Ckinetic energy against time graph: starts at maximum at t=0, falls to zero at T/4, rises to maximum at T/2, falls to zero at 3T/4, rises to maximum at T, and repeats
4. Dkinetic energy against time graph: starts at zero at t=0, rises to maximum at T/4, falls to zero at T/2, rises to maximum at 3T/4, falls to zero at T, and repeats

As printed in the paper