(a(i))[1]
Define power in terms of work done and elapsed time.
(a(ii))[2]
Use your result in (i) to show that power can also be written as force multiplied by velocity.
(b(i))[3]
A lorry travels up a road inclined at $9.0^{\circ}$ to the horizontal, as shown in Fig. 2.1. Its mass is $2500\,\text{kg}$ and it is moving at a steady speed of $8.5\,\text{m s}^{-1}$. Air resistance is negligible. Calculate the useful power from the engine needed to drive the lorry up the road.
(b(ii))[2]
State two reasons why the lorry's rate of change of potential energy is the same as the power calculated in (i).