Mathematics 9709 · AS & A Level · Energy, work and power
Energy, work and power — practice question
A block of mass $20\,\text{kg}$ is drawn from the base to the top of a slope. The slope is $10\,\text{m}$ long and makes an angle of $4.5^\circ$ to the horizontal. The block has speed $2.5\,\text{m}\,\text{s}^{-1}$ at the bottom of the slope and $1.5\,\text{m}\,\text{s}^{-1}$ at the top of the slope.
(i)[3]
Determine the loss of kinetic energy and the gain in potential energy of the block.
(ii)[2]
Since the work done against the resistance to motion is $50\,\text{J}$, determine the work done by the pulling force acting on the block.
(iii)[2]
Also given that the pulling force is constant and acts at $15^\circ$ above the slope, determine its magnitude.
Worked solution & mark scheme
This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Apply energy: $\tfrac12 m(u^2 - v^2)$ or $mgL\sin\alpha$” …