Physics 9702 · AS & A Level · Stress and strain

Stress and strain — practice question

A rocket is fired vertically from Earth’s surface. Fig. 1.1 shows how the rocket’s velocity changes with time during the first 20 s after it is launched.
(a)[1]

Give the definition of acceleration.

(b(i))[1]

Find the acceleration of the rocket.

(b(ii))[2]

Show that the height of the rocket above the Earth’s surface at 20 s after launch is 3.2 km.

(c(i))[2]

The rocket’s mass in (b) is $2.9 \times 10^6\,\text{kg}$. Take this mass to stay constant. For this rocket, from launch to its height 20 s later: calculate the increase in gravitational potential energy $\Delta E_P$.

(c(ii))[2]

Calculate the increase in kinetic energy $\Delta E_K$.

(c(iii))[2]

Determine the mean power output of the rocket engines. Assume resistive forces are negligible.

Worked solution & mark scheme

This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: how quickly velocity changes with time

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