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As per the given figure, a small ball P slides down the quadrant of a circle and hits the other ball Q of equal mass which is initially at rest. Neglecting the effect of friction and assume the collision to be elastic, the velocity of ball Q after collision will be (g=10 m/s²)

Asked in JEE Main 30th Jan 1st Shift 2023 · Velocity exchange and mass ratios

• (1) 4 m/s
• (2) 0
• (3) 0.25 m/s
• (4) 2 m/s

Step-by-step solution

Why the other options are wrong

• (1) Comes from forgetting the square root, v²=2gh=4.
• (2) Comes from swapping the roles: it is P that stops, Q that moves.
• (3) No single slip gives 0.25 m/s; it would need a drop of about 3 mm.

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