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A tunnel is dug along a diameter of the ...

A tunnel is dug along a diameter of the earth. Find the force on a particle of mass m placed in the tunnel at a distance x from the centre.

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The correct Answer is:
C
Mass of earth `M=(4/3)piR^3rho`
mass of the imagiN/Ary sphere having
`radius =x, M'=(4/3)pir^3rho`
M'/M=x^3/R^3`

`:. GravitatioN/Asl foce on f
`=(GMm)/x^2`
`rarr F=(GMx^3m)/(R^3x^2)=(GMm)/R^3x`
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