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Find the two alternative values of the speed of $P$ after the collision.
Mathematics 9709 · AS & A Level · Momentum
Momentum — practice question
Particles $P$ and $Q$, with masses $0.1\,\text{kg}$ and $0.4\,\text{kg}$ respectively, can move freely on a smooth horizontal plane. $P$ is launched at a speed of $4\,\text{m s}^{-1}$ towards stationary $Q$. After $P$ and $Q$ collide, they have equal speeds.