Mathematics 9709 · AS & A Level · Energy, work and power
Energy, work and power — practice question
A particle with mass $1.2\,\text{kg}$ travels along the straight line $AB$. It is launched from $A$ towards $B$ at a speed of $7.5\,\text{m s}^{-1}$ and a resistance force acts on it. The work done against this resistance force as it moves from $A$ to $B$ is $25\,\text{J}$.
(i)[2]
Since $AB$ is horizontal, determine the speed of the particle at $B$.
(ii)[3]
Instead, $AB$ is inclined at $30^\circ$ below the horizontal, and the particle’s speed at $B$ is $9\,\text{m s}^{-1}$. The work done against the resistance force is still unchanged. Determine the distance $AB$.
Worked solution & mark scheme
This 5-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Apply KE equation: $\tfrac12(1.2)(7.5)^2 - \tfrac12(1.2)v^2 = 25$” …