A truck of mass 500 kg moving at 4 m/s collides with another truck of mass 1500 kg moving in the same direction at 2 m/s.What is their common velocity just after the collision if they move off together?

Mass of first truck (m1) =500kg Speed of first truck (u1) =4m/s Mass of second truck (m2) =1500kg Speed of second truck (u2) =2m/s The combined mass of both trucks, m=1500+500=2000kg According to the law of conservation of momentum, combined velocity v is given by m1u1+m2u2=mv 500×4+1500×2=2000×v v= (2000+3000)/(2000) = 2.5m/s