Momentum is a protector the mass and the velocity of a moving object. Momentum= mass*speed For Car A: Mass:1,000 kilograms Velocity: 40 meters/second; Momentum=1,000 kg*40 m/s =40000kg.m/s For Car B: Mass: 4,000 kilograms Velocity 10 meters/second; Momentum=4000kg*10m/s =40000kg.m/s Both cars require the same amount of force to stop. This is because they have the same momentum.
