The student looked at the photograph and noticed that the angle between the paths of the two balls after the collision was not 90°. He modelled the collision on a computer.

He used the same initial conditions for ball 1 and the same value of θ. The

computer calculated the total kinetic energy after the collision for a range of

angles φ. The following graph was produced.

Measure φ from the photograph and use the graph to suggest why the angle

between the paths is not 90°.

φ = 45° to 52°

Use of graph with their angle to determine total kinetic energy after the collision

Statement that it is an inelastic collision

Or Statement that kinetic energy is not conserved

(dependent on candidate attempting MP1 and MP2)