A heavy car A of mass 2000 kg travelling at 10 m/s has a head-on collision with a sports car B of mass 500 kg. If both cars stop dead on colliding, what was the velocity of car B?
Applying conservation of momentum,
P1 = P2
Mass of car A be 2000kg
Mass of car B be 500kg
Velocity of car A before impact = Va = 10m/s
Velocity of car B before impact = Vb=?
Velocity of car A after impact = 0
Velocity of Car B after impact = 0
2000 Va + 500Vb = 2000×0 + 500×0
2000 × 10 + 500Vb = 0
Vb = - 20000/500 = - 40m/s
Negative sign shows that direction of Va and Vb are opposite.