MCQ Detailed View

Escape velocity is the minimum speed an object needs to break free from a planet or moon’s gravitational pull without further propulsion. It depends on two key factors:

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  The mass of the celestial body (M)

  
  


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  The radius of the celestial body (R)

  
  

The formula is:

ve=2GMRv_e = \sqrt{\frac{2GM}{R}}ve=R2GM

Where $G$ is the universal gravitational constant.

The Moon has significantly less mass than Earth, only about 1/81 of Earth's mass, and a smaller radius, about 1/4 of Earth's radius. A smaller mass means weaker gravitational pull, making it easier for an object to escape. While a smaller radius tends to increase escape velocity, the effect of low mass is much stronger. As a result, the escape velocity on the Moon is much lower than Earth's.

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  Escape velocity on Earth: ≈ 11.2 km/s

  
  


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  Escape velocity on the Moon: ≈ 2.38 km/s

  
  

This is why spacecraft can launch from the Moon with much less fuel compared to Earth. It also explains why the Moon cannot hold a thick atmosphere—the weaker gravitational force allows gases to escape more easily. Options 2, 3, and 4 are incorrect because:

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  A smaller radius alone does not make escape velocity larger when mass is low.

  
  


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  Escape velocity is not a universal constant, it varies with celestial body properties.

  
  


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  Time of day has no effect on escape velocity.

  
  

Thus, the correct statement is:

✅ Less than on Earth due to its lower mass and smaller radius.