Question

Question 6.17 The bob A of a pendulum released from 30° to the vertical hits another bob B of the same mass at rest on a table as shown in Fig. 6.15. How high does the bob A rise after the collision? Neglect the size of the bobs and assume the collision to be elastic.

Chapter Work, Energy And Power Page 137

Answer 1

Hi----------

we know that the in elastic collision the linear momentum is conserved .
linear momentum =mass x velocity =mv

here mass of A and B are same.

so if elastic collision occur then A bobs complete transfer it momentum on bobs B

hence, A dont rise again .

hope it help u
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we know that

Answer 2

we know,
in perfectly elastic head -on collision ,
their velocities are interchanged .

in above case , Bob B is at rest and Bob A is collides with Bob B with same speed. hence, after collision Bob A comes to rest and Bob B starts to move with same speed of Bob A .
Hence, Bob A will not rise after collision .