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?

Let

m1=500,


m2=1500


u1=4m/s


u2=2m/s


v1=v2 (since after collision they stuck together)


According to law of conservation of momentum,


m1u1 + m2u2 = m1v1 + m2v2


500 x 4 + 1500 x 2 = (500 + 1500) v


5000 = 2000v


v = 5000/2000


v = 2.5m/s


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