### Gravitation Question 11

#### Question 11 - 30 January - Shift 1

If the gravitational field in the space is given as $(-\frac{K}{r^{2}})$. Taking the reference point to be at $r=2 cm$ with gravitational potential $V=10 J / kg$. Find the gravitational potential at $r=3 cm$ in SI unit (Given, that $K=6 J cm / kg$ )

(1) 9

(2) 11

(3) 12

(4) 10

## Show Answer

#### Answer: (2)

#### Solution:

#### Formula: Universal Law of Gravitation, Gravitational Potential

$-\frac{dV}{dr}=-\frac{k}{r^{2}} \Rightarrow \int _10^{V} dV=\int_2^{3} \frac{k}{r^{2}} dr$

$V-10=k[\frac{1}{2}-\frac{1}{3}]$

$V-10=\frac{k}{6} \Rightarrow V=11$ volts