Mathematics 9709 · AS & A Level · Energy, work and power
Energy, work and power — practice question
A block with mass $25\,\text{kg}$ is dragged over level ground by a force of size $50\,\text{N}$ that acts at $10^{\circ}$ above the horizontal. It begins at rest and moves $20\,\text{m}$. A constant resistive force of size $30\,\text{N}$ opposes the motion.
(i)[2]
Determine the work done by the pulling force.
(ii)[2]
Apply an energy method to determine the block’s speed after it has travelled $20\,\text{m}$.
(iii)[2]
Determine the maximum power produced by the $50\,\text{N}$ force.
(iv)[4]
Determine how long it takes the block to stop after it reaches the bottom of the inclined plane.
Worked solution & mark scheme
This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Work done $= Fd\cos\theta = 50\cos10 \times 20$” …