MCQ Detailed View

Escape velocity is defined as the minimum speed an object must reach to completely overcome a planet’s gravitational pull and move away indefinitely without additional thrust. For Earth, the escape velocity is approximately 11.2 km/s.

If a rocket is launched with a velocity lower than escape velocity, it does not have enough kinetic energy to overcome Earth’s gravity. As the rocket ascends, gravity continuously slows it down. If no further propulsion is provided, its speed will reduce to zero at some maximum height, and then it will fall back to Earth under gravitational attraction.While rockets can still enter orbit without reaching escape velocity, they require precise horizontal velocity to balance gravitational pull and centripetal force. Simply launching upward with less than escape velocity, without achieving orbital speed, will not place the rocket into a stable orbit—it will instead follow a curved path and eventually return to Earth.

Key points:

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  Escape velocity (vₑ):

  
  

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

Where $M$ is Earth’s mass, $R$ is its radius, and $G$ is the universal gravitational constant.

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  If actual velocity v<vev < vₑv<ve, the object cannot escape gravitational attraction.

  
  


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  Rockets require either escape velocity to leave Earth permanently or orbital velocity to circle around Earth.

  
  

This principle explains why massive rockets use multi-stage boosters: they need enough thrust to overcome gravitational pull or to reach a stable orbit before falling back.

✅ Correct Answer: Fall back to Earth.