Q.

Assertion (A): A body of mass m1 collides head on elastically with another body of mass m2 at rest. The ratio of the final energy of the first body to the final energy of the second body is (m1−m2)24m1m2

Reason (R): The collision is perfectly elastic and the coefficient of restitution is 1.

1 Both (A) and (R) are true and (R) is the correct explanation of (A)  
2 Both (A) & (R) are true but (R) is not correct explanation of (A)  
3 (A) is true and (R) is false  
4 Both (A) and (R) are false  

Ans.

(1)

K.E.1=12m1v12;    K.E.2=12m2v22

K.E.1K.E.2=12(m1-m2m1+m2)2u1212m2(2m1m1+m2)2u12=(m1-m2)24m1m2

For perfectly elastic collision, e=1