Work Energy And Power Question 167
Question: A body of mass 2kg is moving with velocity 10 m/s towards east. Another body of same mass and same velocity moving towards north collides with former and coalsces and moves towards north-east. Its velocity is [CPMT 1997; JIPMER 2000]
Options:
A) 10 m/s
B) 5 m/s
C) 2.5 m/s
D) $ 5\sqrt{2}m/s $
Show Answer
Answer:
Correct Answer: D
Solution:
Initial momentum = $ \vec{P}=mv\hat{i}+mv\hat{j} $
$ |\vec{P}|=\sqrt{2}mv $
Final momentum = $ 2m\times V $
By the law of conservation of momentum $ 2m\times V=\sqrt{2}\ mv $
therefore $ V=\frac{v}{\sqrt{2}} $
In the problem $ v=10m/s $ (given) \ $ V=\frac{10}{\sqrt{2}}=5\sqrt{2}\ m/s $
