Question

At some point, the gravitational potential and also the gravitational field due to earth is zero. The point is

• A. on earth's surface
  
• B. below earth's surface
  
• C. at a height $R_{\text{e}}$ from earth's surface ($R_{\text{e}}$ = radius of the earth)
  
• D. at infinity
  

Answer 1

The correct option is D at infinity


Gravitational field is zero at both the point centre of Earth and infinity.

Due to point mass gravitational field is $E_{\text{g}}=-\frac{GM}{r^2}$where as for solid sphere gravitational field is, $E_{\text{g}}=-\frac{GMr}{R^3}$

Where as gravitational potential is only zero at infinity.

$V_{\text{g}}=-\frac{GM}{r}$