Mathematics 9709 · AS & A Level · Energy, work and power
Energy, work and power — practice question
A tractor with mass $3700\,\text{kg}$ moves along a straight horizontal road at a steady speed of $12\,\text{m s}^{-1}$. The total resistance opposing motion is $1150\,\text{N}$.
(i)[1]
Find the power output from the tractor’s engine.
(ii)[3]
The tractor reaches a hill inclined at $4^\circ$ above the horizontal. The power output is raised to $25\,\text{kW}$ and the resistance to motion stays the same. Find the deceleration of the tractor at the instant it starts to climb the hill.
(iii)[2]
Find the constant speed the tractor could keep on the hill while operating at this power.
Worked solution & mark scheme
This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Calculate power from $P = Fv$, giving $1150 \times 12 = 13800\,\text{W}$” …