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Mechanics

Scorching goIITian

Joined:	5 Apr 2008
Post:	269

21 Nov 2008 21:15:17 IST

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Gravity

Engineering Entrance , Medical Entrance , AIPMT , JEE Main , AIIMS , JEE Advanced , Physics , Mechanics

Hello,

I read in a book that the formula is not applicable to calculate 'g' inside the earth's surface.

Is it true.

If yes then why.

Comments (3)

MAK

Hot goIITian

Joined: 19 Nov 2008

Posts: 134

21 Nov 2008 21:21:37 IST

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ya it is true...

as we go below d earth surface... d effective mass of earth dat exerts gravitational force will decrease and also d radius will decrease... hence v cannot use d formula g = GM / R^2 ...

rather d formula would be... g' = (GM / R^2).(1-h/R) = g(1-h/R)...

hope u got it...

rate if found useful...

Bhimsen Padalkar

Scorching goIITian

Joined: 29 Oct 2008

Posts: 298

21 Nov 2008 21:22:45 IST

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Because inside the earth, the gravitational force is not exrted by whole mass of earth.

Suppose, an object is at depth 'd' from surface of earth, then only the sphrical mass having radius (R-d) will exert gravitational force on the object.

At depth d, the formula changes as,

Astronomer

Scorching goIITian

Joined: 5 Apr 2008

Posts: 269

10 May 2009 19:54:28 IST

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thanx

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