Physics 9702 · AS & A Level · Potential difference and power

Potential difference and power — practice question

A rocket is fired vertically upward from Earth’s surface. Fig. 1.1 illustrates how the rocket’s velocity varies with time during the first 20 s after launch.
(a)[1]

Define acceleration in words.

(b(i))[1]

Determine the acceleration of the rocket.

(b(ii))[2]

Show that the height of the rocket above the Earth’s surface 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 the height it has reached 20 s after launch: calculate the gain in gravitational potential energy $\Delta E_{P}$.

(c(ii))[2]

Calculate the gain in kinetic energy $\Delta E_{K}$.

(c(iii))[2]

Determine the average power output of the rocket engines, taking resistive forces to be negligible.

Worked solution & mark scheme

This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: the rate at which velocity changes

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