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Gravitation

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Question : 16 of 25
Marks: +1, -0
Assuming the earth to be a sphere of uniform mass density, how much would a body weigh half way down to the centre of the earth if it weighed 250 N on the surface?
Solution:  
Variation of acceleration due to gravity g with depth d is
g′=g(1−dR)g'=g\left(1-\frac{d}{R}\right)
Weight of body at a depth d
mg′=mg(1−dR)m g'=m g\left(1-\frac{d}{R}\right)
=250(1−R2R)=250\left(1-\frac{\frac{R}{2}}{R}\right)
=125N.=125 N.
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