A body of mass 2   kg moving with a speed of 4   m   s - 1 makes an elastic collision with…

A body of mass 2 kg moving with a speed of 4 m s-1 makes an elastic collision with another body at rest and continues to move in the original direction but with one fourth of its initial speed. The speed of the two body centre of mass is $x/10$. Find the value of x.

Solution

pi=pf

2×4=2×1+m2×v2

m2v2=6 (1)

By coefficient of restitution, 
1=v2-14v2=5 m s-1

by (i)

m2×5=6

m2=1.2 kg

vcm=m1v1+m2v2 m1+m2

vcm=2×1+1.2×52+1.2=83.2=2510

x=25

Asked in: JEE Main 2021 (25 Jul Shift 1)

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