Q107 / 150 · MHT CET 2011 · Physics
The mass of earth is 81 times that of the moon and the radius of the earth is $3.5$ times that of the moon. The ratio of the escape velocity on the surface of earth to that on the surface of moon will be
- A$0.2$
- B$2.57$
- Correct answerC$4.81$
- D$0.39$
Solution
Escape velocity, $v_{e}=\sqrt{\frac{2 G M}{R}}$
$\therefore$
$$
\frac{v_{e}}{v_{m}}=\sqrt{\frac{M_{e} R_{m}}{M_{m} R_{e}}}
\frac{v_{e}}{v_{m}}=\sqrt{\frac{81}{3.5}}=4.81
$$
Hence, the correct answer is option: 'C'.