Student Login

Home›Chapters›Centre of Mass PYQs›Motion of Centre of Mass›Question 8

NEET 2015 (AIPMT, Cancelled Paper) · Motion of Centre of Mass

Motion of Centre of Mass question from NEET 2015 (AIPMT, Cancelled Paper)

Q8NEET 2015 · AIPMT · CANCELLED PAPERMedium

Motion of Centre of Mass

Two spherical bodies of mass M and 5M and radii R and 2R are released in free space with initial separation between their centres equal to 12R. If they attract each other due to gravitational force only, then the distance covered by the smaller body before collision is:

Show answer and solution

Answer: (a)

Only mutual gravity acts, so the CM stays fixed; distances moved are inversely proportional to masses.
They touch when the centres are $R + 2R = 3R$ apart, so the gap closed is $12R - 3R = 9R$ .
Smaller body: $d = \frac{5M}{M+5M}\cdot 9R = \frac{5}{6}\cdot 9R = 7.5R$
So the answer is (a) $7.5R$ .

Report a mistake

More questions on Motion of Centre of Mass

A boy of mass 20 kg is standing on a 80 kg free to move long cart. There is negligible…JEE Main 2013 (23 Apr, Shift 1)
A projectile of mass M is fired so that the horizontal range is 4 km. At the highest…JEE Main 2013 (23 Apr, Shift 1)
Two persons of masses 55 kg and 65 kg respectively, are at the opposite ends of a boat…NEET 2012 (AIPMT, Prelims)
Two particles which are initially at rest, move towards each other under the action of…NEET 2010 (AIPMT, Prelims)
A body A of mass M while falling vertically downwards under gravity breaks into…JEE Main 2005 (AIEEE)
Two identical particles move towards each other with velocity 2v and v respectively. The…JEE Main 2002 (AIEEE)
Given below are two statements: Statement I: For a mechanical system of many particles…JEE Main 2026 (22 Jan, Shift 2)
Two identical bodies A and B of equal masses have initial velocities v₁ = 4i m/s and v₂ =…JEE Main 2026 (6 Apr, Shift 2)