AP EAMCET Engineering 22 Sep 2020 Shift 2 Paper

Gravitational potential energy on the surface of earth,
U1=−‌

GMm

R

...(i)
where, M= mass of earth. and
R= radius of earth.
Gravitational potential energy at height h=3R is given as
U2=−‌

GMm

R+h

=−‌

GMm

R+3R

U2=−‌

GMm

4R

...(ii)
∴ Change in gravitational potential energy,
[from Eqs. (i) and (ii)]
=−‌

GMm

4R

+‌

GMm

R

=‌

3

4

⋅‌

GMm

R

=‌

3

4

⋅‌

gR2⋅m

R

  [∵GM=gR2]
=‌

3

4

mgR