A metallic bob X of mass m is released from position A. It collides elastically with another identical bob Y placed at rest at position B on a horizontal frictionless table. The angle AOB is 30°. How high does the bob X rise immediately after the collision?
A.To the same height as that of position A on the other side in the same trajectory
B.To half the height as that of position A on the other side along the same trajectory
C.The same height at position A
D.It stops at position B✓ Correct
Explanation
In an elastic collision between two bodies of equal mass where one is initially at rest, the moving body transfers its entire velocity to the stationary body and itself comes to rest. Thus bob X, after striking bob Y of identical mass elastically, stops at position B while Y moves off with X's velocity. Since X is at rest immediately after collision, it does not rise — it stops at position B.
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