Mathematics 9709 · AS & A Level · Energy, work and power
Energy, work and power — practice question
A and B lie 50\,\text{m} apart along a straight path inclined at an angle $\theta$ to the horizontal, with $\sin\theta = 0.05$, and A is above B. A block of mass $16\,\text{kg}$ is pulled down the path from A to B. It starts from rest at A and arrives at B with speed $10\,\text{m s}^{-1}$. The work done by the pulling force on the block is $1150\,\text{J}$.
(i)[3]
Calculate the work done against resistance to motion.
(ii)[2]
The block is now pulled up the path from B to A. The work done by the pulling force and the work done against the resistance to motion are unchanged from the downward journey. Show that the speed of the block when it reaches A is the same as its speed when it started at B.
Worked solution & mark scheme
This 5-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Use work done by pulling force $=$ increase in KE $-$ decrease in PE $+$ work done by resistance” …