Two gliders move directly towards one another along a horizontal air track. Glider P has mass $0.30\ \text{kg}$ and is travelling at a constant speed of $1.2\ \text{m s}^{-1}$. Glider Q has mass $0.60\ \text{kg}$ and is travelling at a constant speed of $1.8\ \text{m s}^{-1}$. The gliders undergo a perfectly elastic collision. What are the speeds of the two gliders after the collision?
- Aspeed of P: $1.2\ \text{m s}^{-1}$; speed of Q: $0.6\ \text{m s}^{-1}$
- Bspeed of P: $2.0\ \text{m s}^{-1}$; speed of Q: $1.4\ \text{m s}^{-1}$
- Cspeed of P: $2.8\ \text{m s}^{-1}$; speed of Q: $0.2\ \text{m s}^{-1}$
- Dspeed of P: $3.6\ \text{m s}^{-1}$; speed of Q: $0.6\ \text{m s}^{-1}$