Collision of Bodies
Let the two bodies 1 & 2 have momentum p1 & p2 before they collided with each other. After collision their momentum are p1’ and p2’ respectively.
By Newton’ s Second law, F = dp / dt For 1: F12 =( p1’ – p1) / ∆t For 2: F21 =( p2’ – p2) / ∆t
By Newton’ s Third law, F 12 =- F21( p1’ – p1)/ ∆t =( p2’ – p2) / ∆t( p1’ – p1) =( p2’ – p2)
p1’ + p2’ = p1 + p2
Conclusion: Final momentum of the system = Initial momentum of the system
Problem: A railway truck A of mass 3 * 10 4 kg travelling at 0.6 m / s collides with another truck B of half its mass moving in the opposite direction with a velocity of 0.4 m / s. If the trucks couple automatically on collision, find the common velocity with which they move.