Question

Escape velocity from earth is $11.2km/sec$. Another planet of same mass has radius $\frac{1}{4}$ times that of earth. What is the escape velocity from this planet ?

• A. $11.2km/sec$
• B. $44.8km/sec$
• C. $22.4km/sec$
• D. $5.6km/sec$

Answer 1

Answer: (C)

$22.4km/sec$

Escape velocity , $v_e=\sqrt{\frac{2G{M}_e}{R_e}}=11.2km/s$

For $R^{\prime }=\frac{R_e}{4}{M}^{\prime }=M_e$

$v_e^{\prime }=\sqrt{\frac{2G{M}_e}{\frac{R_e}{4}}}=2v_e=22.4km/s$