A Car of Mass M Travelling at 40

Multiple Choice

A car of mass m travelling at 40.0 km/hr collides head-on with a stationary car of equal mass, and stays attached until the pair come to a stop. The car in motion does NOT apply the brakes, whereas the stationary car has a braking force of 0.2mg. At what distance from the collision site does the pair of cars come to rest?

A) 4.0 m
B) 7.9 m
C) 11 m
D) 16 m