A bumper car A of mass 180 kg (including its driver) travels on a horizontal, low-friction track and collides head-on with a stationary bumper car B of mass 270 kg (including its driver). Immediately after the collision, car B moves forward with a speed of 3.2 m s-1 and car A recoils in the opposite direction with a speed of 1.2 m s-1.
What was the initial speed of bumper car A?
3.6 m s−13.6\text{ m s}^{-1}3.6 m s−1
4.8 m s−14.8\text{ m s}^{-1}4.8 m s−1
6.0 m s−16.0\text{ m s}^{-1}6.0 m s−1
2.4 m s−12.4\text{ m s}^{-1}2.4 m s−1
