Work Energy And Power Question 161
Question: Two putty balls of equal mass moving with equal velocity in mutually perpendicular directions, stick together after collision. If the balls were initially moving with a velocity of $ 45\sqrt{2}m{s^{-1}} $ each, the velocity of their combined mass after collision is [Haryana CEE 1996; BVP 2003]
Options:
A) $ 45\sqrt{2}m{s^{-1}} $
B) $ 45m{s^{-1}} $
C) $ 90m{s^{-1}} $
D) $ 22.5\sqrt{2}m{s^{-1}} $
Show Answer
Answer:
Correct Answer: B
Solution:
Initial momentum $ \vec{P}=m45\sqrt{2}\ \hat{i}+m45\sqrt{2}\ \hat{j} $
therefore $ |\vec{P}|=m\times 90 $
Final momentum $ 2m\times V $
By conservation of momentum $ 2m\times V=m\times 90 $ \ $ V=45m/s $
