Work Energy And Power Question 77

Question: A body of mass m moving with velocity v collides head on with another body of mass 2m which is initially at rest. The ratio of K.E. of colliding body before and after collision will be [Roorkee 1982]

Options:

A) 1 : 1

B) 2 : 1

C) 4 : 1

D) 9 : 1

Show Answer

Answer:

Correct Answer: D

Solution:

K.E. of colliding body before collision =12mv2

After collision its velocity becomes v=(m1m2)(m1+m2)v=m3mv=v3 \ K.E. after collision 12mv2

=12mv29 Ratio of kinetic energy = K.E.beforeK.E.after=12mv212mv29=9:1



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