A remote-controlled rocket cart of mass 0.40 kg travels along a low-friction linear track at a constant velocity of 12.0 m s-1. A brief retro-thrust is fired in the opposite direction to the cart's motion, changing its momentum by 6.2 kg m s-1.
What is the speed of the cart after the retro-thrust has completed?
3.5 m s−13.5\text{ m s}^{-1}3.5 m s−1
5.8 m s−15.8\text{ m s}^{-1}5.8 m s−1
15.5 m s−115.5\text{ m s}^{-1}15.5 m s−1
27.5 m s−127.5\text{ m s}^{-1}27.5 m s−1
