Physics 9702 · AS & A Level · Momentum and Newton's laws of motion

Momentum and Newton's laws of motion — practice question

A skydiver leaves an aircraft at $t = 0$ and moves straight downward. Figure 2.1 shows how her velocity $v$ changes with $t$.
(a(i))[1]

From Fig. 2.1, state the terminal velocity of the skydiver.

(a(ii))[2]

Using a suitable line drawn on Fig. 2.1, determine the skydiver’s acceleration at time $t = 9.0\ \text{s}$.

(b)[3]

The combined mass of the skydiver and her equipment is $68\ \text{kg}$. Upthrust on the skydiver can be ignored. Once terminal velocity has been reached, the skydiver opens her parachute at time $t_1$. The drag force acting on the skydiver is $1800\ \text{N}$. Determine both the size and the direction of the skydiver’s acceleration at time $t_1$.

(c(i))[2]

The parachute is completely open at time $t_2$. At a later time $t_3$ the skydiver has a steady velocity of $5.7\ \text{m s}^{-1}$. Describe and explain how the magnitude of her acceleration varies with time between $t_2$ and $t_3$.

(c(ii))[2]

Calculate the change in momentum of the skydiver between time $t_1$ and time $t_3$.

Worked solution & mark scheme

This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: Gives speed as $39\,\text{m s}^{-1}$

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