Physics 5054 · O Level · Motion

Motion — practice question

Fig. 1.1 depicts two trolleys. A wooden rod is attached to the front of trolley A, while trolley B is initially stationary. When trolley A moves to the right, the rod goes into the modelling clay. Trolley A slows down and trolley B begins to move. The two trolleys then stay stuck together and keep travelling to the right. Fig. 1.1 labels: trolley A, trolley B, wooden rod, modelling clay. Fig. 1.2 presents the speed-time graph for the two trolleys. The vertical axis shows speed in m/s and the horizontal axis shows time $t$/s. The lines are labelled trolley A, trolley B, and trolley A and B. The trolleys begin to collide at time $t = 0.30\,\text{s}$. At $t = 0.50\,\text{s}$, both trolleys are moving at the same speed.
(a(i))[1]

State how Fig. 1.2 indicates that, during the collision, trolley B has a constant acceleration.

(a(ii))[1]

Describe how the graph in Fig. 1.2 shows that the magnitude of trolley B’s acceleration is greater than the magnitude of trolley A’s deceleration.

(a(iii))[2]

Calculate the acceleration of trolley B when $t = 0.40\,\text{s}$.

(b)[2]

The mass of trolley A is $0.80\,\text{kg}$. The mass of trolley B is $0.60\,\text{kg}$. Show that momentum is conserved in the collision.

(c)[2]

In a different collision between the same trolleys, the rod and modelling clay are missing. Trolley A strikes trolley B with the same initial speed. Explain why the force between the trolleys is greater in this collision.

Worked solution & mark scheme

This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: A straight line on the speed-time graph

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