Question
A point particle is held on the axis of a ring of mass m and radius r at a distance r from its centre C. When released, it reaches C under the gravitational attraction of the ring. Its speed at C will be
BITSAT
Physics
Gravitation
2021
BITSAT 2021
BITSAT Physics Question (2021) — Solution
Options
- A. 2 G m r ( 2 -1)
- B. G m r
- C. 2 G m r (1- 1 2 )
- D. 2 G m r
Answer
C. 2 G m r (1- 1 2 )
Step-by-step solution
Let ' M ' be the mass of the particle Now, E_ initial =E_ final i.e. GMm 2 r +0= GM m r + 1 2 MV ^ 2 or, 1 2 MV ^ 2 = GM m r [1- 1 2 ] 1 2 ~V ^ 2 = G m r [1- 1 2 ] or, V = 2 Gm r (1- 1 2 )
Related: Physics — Gravitation · All PYQ Banks