Two bodies of masses 3kg and 5kg moving with velocities 2 m/s and V m/s respectively in opposite directions collide. If they move together after collision with velocity 3.5 m/s in the direction of the 5kg mass, find the value of V.
- 7.8 m/s
-
6.8 m/s
- 5.6 m/s
- 4.6 m/s
The correct answer is: B
Explanation
Since the bodies are in an opposite direction, one takes the negative velocity.
\(m_{1}v_{1} + m_{2}v_{2} = (m_{1} + m_{2})v\) (Momentum when the two bodies move in the same direction after collision)
\(3(-2) + 5(V) = (3 + 5)3.5\)
\(-6 + 5V = 28 \implies 5V = 34; V = 6.8 m/s\)