Question
Determine the escape velocity of a body from the moon. Take the moon to be a uniform sphere of radius 1.74 x 106 m and mass 7.36 x 1022 kg. Does your answer throw light on why the moon has no atmosphere? (G = 6.67 x 10-11 Nm2/kg2)
Solution
Escape velocity from the surface of the moon is,
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where,
M is the mass of the moon, and
R is radius of the moon.
Here, we have

∴ Escape velocity is,
Since escape velocity for the moon is 2.38 km/sec which is small as compared to the average speed of gas molecules at the moon, therefore the moon cannot bind the atmosphere.
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where,
M is the mass of the moon, and
R is radius of the moon.
Here, we have



∴ Escape velocity is,


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Since escape velocity for the moon is 2.38 km/sec which is small as compared to the average speed of gas molecules at the moon, therefore the moon cannot bind the atmosphere.