Correct Answer - Option 2 : The gravitational force is comparitively small
The reason is The gravitational force is comparitively small. So, the escape velocity is small and gases have lesser gravitational force.
Concept:
Escape velocity
- It is the minimum velocity with which a body should be projected from the surface of the planet so that the body reaches infinity.
- It is given as,
\(⇒ v_{e}=\sqrt{\frac{2GM}{R}}\)
where ve = escape velocity, G = gravitational acceleration, M = mass of the planet and R = radius of the planet
Explanation:
Given - mass of the moon (Mm) = 7.4×1022 kg, radius of the moon (Rm) = 1.75×106 m and G = 6.67×10-11 Nm2/kg2
- So the escape velocity of the moon is given as,
\(⇒ v_{e}=\sqrt{\frac{2GM_{m}}{R_{m}}}\)
⇒ ve = 2.38 km/s
- Since the escape velocity of the moon is less than the root means square velocity of the gas molecules on the moon, so there is no atmosphere on the moon.