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Physics · PYQ NEET UG 2026
हिन्दीBob ( B ) of mass ( m ) at rest is hanging vertically from the ceiling via a massless string of length ( 10 \text{ m} ), as shown in the figure. Point mass ( A ) of mass ( m ) travelling horizontally with speed ( 10 \text{ ms}^{-1} ) hits bob ( B ) elastically. The bob ( B ) rises ( h ) meter after the collision. Taking the acceleration due to gravity ( g = 10 \text{ ms}^{-2} ) and neglecting the size of the bob, the value of ( h ) is :
Correct answer · Option 3
5
Explanation
In a 1D elastic collision between two equal masses where one is at rest, velocities are interchanged. Thus, bob B acquires speed ( v = 10 \text{ ms}^{-1} ). Height ( h = \frac{v^2}{2g} = \frac{10^2}{2 \times 10} = 5 \text{ m} ).
