Physics 9702 · AS & A Level · Equations of motion

Equations of motion — practice question

A toy aircraft lifts a small block straight upward, as shown in Fig. 2.1. While the block is rising, the string snaps at time $t = 0$. At first the block still moves upward, then it drops and reaches the ground at time $t = 0.90\,\text{s}$. Fig. 2.2 shows how the block’s velocity $v$ changes with time $t$. Air resistance is negligible.
(a)[1]

State the property of the graph in Fig. 2.2 that indicates the block has constant acceleration.

(b)[3]

Use Fig. 2.2 to determine the height of the block above the ground when the string breaks at time $t = 0$.

(c)[2]

The block’s weight is $0.86\,\text{N}$. Calculate the change in gravitational potential energy of the block from time $t = 0$ to time $t = 0.90\,\text{s}$.

(d)[2]

On Fig. 2.3, sketch a graph to show how the distance moved by the block varies with time $t$ from $t = 0$ to $t = 0.20\,\text{s}$. No numerical distance values are needed.

(e)[1]

A block with a larger mass is now let go from the same height with the same upward velocity. Air resistance is still negligible. State and explain the effect, if any, of the larger mass on the speed at which the block reaches the ground.

Worked solution & mark scheme

This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: states that the graph has a steady gradient

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