Physics - Gravitation Question with Solution | TestHub

PhysicsGravitationField & ForceEasy2 minPYQ_2018
PhysicsEasysingle choice

A spherically symmetric gravitational systom of particles has mass density ρ=ρ0 for rR0 for r>R where, ρ0 is a constant. A test mass can undergo circular motion under the influence of the gravitational field of particles. Its speed v as a function of distance r(0<r<) from the centre of the system is represented by

Options:

Answer:
C
Solution:

When rR, then force on the test mass n at the surface of the sphere =mg

Force on the test mass at distance r from the centre of sphere is

If r<R, then F=GMmR2·rR=GMmR3·r

mv2r=GMmR3·r

v α r

If r>R then F=GMmr2

Mv2r=GMmr2

 v α 1r

Stream:BITSATSubject:PhysicsTopic:GravitationSubtopic:Field & Force
2mℹ️ Source: PYQ_2018

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