Mathematics 9709 · AS & A Level · Energy, work and power
Energy, work and power — practice question
A body of mass $12\,\text{kg}$ moves down the line of greatest slope on a smooth plane that is inclined at $10^{\circ}$ to the horizontal. It goes through points A and B with speeds $3\,\text{m s}^{-1}$ and $7\,\text{m s}^{-1}$ respectively.
(i)[2]
Determine the rise in kinetic energy of the object as it travels from A to B.
(ii)[3]
Hence determine the distance $AB$, on the assumption that no resisting force acts on the object.
(iii)[3]
The object is now moved up the plane from B to A at constant speed by means of a horizontal force. Determine the magnitude of this force.
Worked solution & mark scheme
This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Apply $\text{KE gain} = \tfrac12 m(v_B^2 - v_A^2)$” …