Question

A body weights 100N on the surface of earth. it's weight at a depth equal to half the radius of earth is?
a) 44.44N
b) 50N
c) 25N
d) 75N​

Answer 1

Answer:

b) 50N

Explanation:

The variation of gravity with depth d is given by

$go = g(1 - \frac{d}{r} )$

Where d is depth and r is radius of earth

for d=r/2

$go = g(1 - \frac{1}{2} )$

i.e

$go = \frac{g}{2}$

Now weight of an object is mg

Here m is the mass

So mg=100N

$m = \frac{100}{g}$

Now mass of an object never changes so

$mgo = \frac{100}{g} go$

$= \frac{100}{2}$

Since

$go = \frac{g}{2}$

so mgo=50N.