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Question: Answered & Verified by Expert
The mass density of a spherical body is given by ρr=kr for rR and ρr=0 for r>R, where r is the distance from the centre. The correct graph that describes qualitatively the acceleration, a, of a test particle as a function of r is :
PhysicsGravitationJEE Main
Options:
  • A
  • B
  • C
  • D
Solution:
1925 Upvotes Verified Answer
The correct answer is:


 For Inside point rR

g=E=Gr20r4πr2drKr          GKr2×4πr22=2πGK=constant

For outside point r>R

E=g= GM r 2 = G r 2 0 R ( 4π r 2 d r )( K r )= 4πKG r 2 [ r 2 2 ] 0 R

E=g=2πKGr2R2

E1r2

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