A body of mass 10 kg moving with a velocity of 5ms−1 hits a body of 1 gm at rest. Find the velocity of the second body after collision assuming it to be perfectly elastic ?
A
10ms−1
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B
5ms−1
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C
15ms−1
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D
0.10ms−1
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Solution
The correct option is A10ms−1 For a perfectly elastic collision, coefficient of restitution is e=1.
Let u and v be the velocities of 10 kg and 1 g masses after collision.
Thus, e=rel. vel.of separationrel. vel. of approach=v−u5−0=v−u5
But, as e=1, we have v−u=5.
Total momentum before collision is P=10×5=50 kg m/s
Total momentum after collision is P=10×(v−5)+0.001×v=10.001v−50