Bob B of mass m at rest is hanging vertically from the ceiling via a massless string of length 10 m, as shown in the figure. Point mass A of mass m travelling horizontally with speed 10 m s^-1 hits bob B elastically. The bob B rises h meter after the collision. Taking the acceleration due to gravity g = 10 m s^-2 and neglecting the size of the bob, the value of h is :

(C) 5. Concept. Elastic collision of equal masses exchanges velocities; then energy conservation for the bob. Step 1. After collision. B moves off at 10 m/s. Step 2. Height. h = (100)/(20) = 5 m (less than the string length, so the string stays taut). Answer. 5 (Option C).

Work, Energy and Power question for NEET (NEET 2026), with solution

Q 11-05-003NEETNEET 2026Top questionEasy

Bob $B$ of mass $m$ at rest is hanging vertically from the ceiling via a massless string of length $10$ m, as shown in the figure. Point mass $A$ of mass $m$ travelling horizontally with speed $10\ \text{m s}^{-1}$ hits bob $B$ elastically. The bob $B$ rises $h$ meter after the collision. Taking the acceleration due to gravity $g = 10\ \text{m s}^{-2}$ and neglecting the size of the bob, the value of $h$ is :

Bob B hanging at rest on a 10 m string, with point mass A approaching horizontally at 10 m/s

← Previous Next question →

Revise the formulasWork, Energy and Power formula sheet: key equations and special cases→

Work, Energy and Power question for NEET (NEET 2026), with solution

More Work, Energy and Power questions