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A body of mass 18kg moving with velocity 4ms-1 collides w...

A body of mass 18kg moving with velocity 4ms-1 collides with another body of mass 6kg moving in the opposite direction with velocity 10ms-1. If they stick together after the collision, find their common velocity.

A.

12 m/s

B.

13 m/s

C.

2m/s

D.

3m/s

Correct answer is A

m1u1 + m2u2 = (m1 + m2)v


m1 = 18kg, m2 = 6kg, u1 = 4ms-1, u2 = -10m/s


18(4) + 6(-10) = (18+6)v


72 - 60 = 24v
12 = 24v
v = 12 m/s