Question

If earth has a mass nine times and radius twice to that of a planet $P$ Then $\frac{v_e}{3} \sqrt{x} ms ^{-1}$ will be the minimum velocity required by a rocket to pull out of gravitational force of $P$, where $v_e$ is escape velocity on earth The value of $x$ is

• A. 1
• B. 18 $
• C. 3$
• D. 2

Answer 1

Answer: (D)

2

Answer 2

v(escape) plant ​=RP​2GMP​​​
=(2Re​​)2G(9Me​​)​​=3ve​2​​
∴x=2