Mathematics 9709 · AS & A Level · Kinematics of motion in a straight line

Kinematics of motion in a straight line — practice question

A particle travels along a straight line, with displacement $s$ metres at time $t$ seconds after departing from a fixed point $O$. It starts from rest and is at points $P$, $Q$ and $R$ at times $t = 5$, $t = 10$ and $t = 15$ respectively, then returns to $O$ at time $t = 20$. The distances $OP$, $OQ$ and $OR$ are $50\,\text{m}$, $150\,\text{m}$ and $200\,\text{m}$ respectively. The diagram displays a displacement-time graph representing the particle’s motion from $t = 0$ to $t = 20$. The graph is formed by two curved sections $AB$ and $CD$ and two straight sections $BC$ and $DE$.
(a)[1]

Determine the speed of the particle for the period from $t = 5$ to $t = 10$.

(b)[2]

Find the acceleration of the particle from $t = 0$ to $t = 5$, assuming it is constant.

(c)[2]

Determine the particle's average speed over the whole motion.

Worked solution & mark scheme

This 5-mark question has a full step-by-step worked solution and mark scheme. One marking point: Correct value of speed $20\text{ m s}^{-1}$

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