What if the decrease in weight of a body of mass 500 kg when it is taken into a mine of depth 1000 km ?
(Radius of earth `R=6400 km, g=9.8 m//s^(2))`

Explanation

Given : `m=500 kg, d=1000 km, R=6400 km, `
`g=9.8 m//s^(2)`
Weight of a body on the surface of the earth
`=500 xx 9.8=4900N`
Weight of a body at depth d,
`W_(d)=m xx g_(d)`
At depth d, `g_(d)=g((R-d))/(R )`
`g_(d)=(9.8(6400-1000))/(6400)`
`g_(d)=9.8 xx 0.843`
`g_(d)=8.268m//s^(2)`
`W_(d)=m xx g_(d)`
`=500 xx 8.268 m//s^(2)`
`W_(d)=4134.3 N`
`W_(d)=4134.3N`
Decrease in weight `=4900-4134.375`
`=765.625N`