Physics 9702 · AS & A Level · Gravitational potential energy and kinetic energy
Gravitational potential energy and kinetic energy — practice question
A motor lifts bricks straight upwards, as shown in Fig. 5.1. The bricks begin from rest and speed up for $2.0\,\text{s}$. They then move at a steady speed of $0.64\,\text{m s}^{-1}$ for $25\,\text{s}$. Lastly, they are slowed to rest over a further $3.0\,\text{s}$. The total mass of the bricks is $25\,\text{kg}$.
(a(i))[2]
Determine the change in kinetic energy of the bricks during the first $2.0\,\text{s}$.
(a(ii))[1]
Determine the change in kinetic energy of the bricks over the following $25\,\text{s}$.
(a(iii))[1]
Determine the change in kinetic energy of the bricks during the final $3.0\,\text{s}$.
(b(i))[3]
The bricks are in a container. The combined weight of the container and bricks is $350\,\text{N}$. Calculate the gain in potential energy for the lifting of the bricks and container when they travel at constant speed.
(b(ii))[2]
Calculate the power needed.
Worked solution & mark scheme
This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “formula for the change in kinetic energy $= \frac{1}{2}mv^2$” …