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 $



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