Mathematics 9709 · AS & A Level · Energy, work and power
Energy, work and power — practice question
Particles $P$ and $Q$, whose masses are $6\,\text{kg}$ and $2\,\text{kg}$ respectively, are initially at rest and separated by $12.5\,\text{m}$ on a rough horizontal plane. The coefficient of friction between each particle and the plane is $0.4$. Particle $P$ is then projected towards $Q$ with speed $20\,\text{m s}^{-1}$.
(a)[3]
Show that just before the collision, the speed of $P$ is $10\sqrt{3}\,\text{m s}^{-1}$.
(b)[4]
Determine the kinetic energy lost in the collision.
(c)[2]
With coefficient of friction between $R$ and the plane equal to $0.4$, find how far particle $R$ travels before it comes to rest.
Worked solution & mark scheme
This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Use horizontal resolution with Newton’s second law to derive $0.4g=6a$ or $-0.4g=6a$.” …