**Question 9.**

**Solve the following problems.If mass of a planet is eight times the mass of the earth and its radius is twice the radius of the earth, what will be the escape velocity for that planet?**

Answer:

Mass of planet M = 8 x mass of earth = 8 x 6 x 1024 kg

Radius of planet R = 2 x radius of earth = 2 x 6.4 x 106 m

G = gravitational constant = 6.67 x 10-11 N m2/kg2

So escape velocity = √

Escape velocity =

= 22.4 km/sec.

So escape velocity of the planet will be 22.4 km/sec.