In Physics, Escape Velocity is the minimum velocity that is sufficient for a body to escape from the gravitational pull of a planet. The Escape Velocity of the same objects might be different on different planets & moons.

The Escape Velocity of an object on the earth is greater than the escape velocity of the same object on the moon.

⇒ The Escape Velocity or Escape Speed of an object on the Earth is around 11.2 km/s.

⇒ The Escape Velocity of an object on the Moon is around 2.3 km/s.

New CBSE Syllabus 2021-22 (PDF): CBSE Curriculum for CBSE Academic Session 2021-22

Formula For Escape Velocity (Earth):

vminimum = (2GM_{E}/R_{E})^{½}

Here,

vminimum: is the minimum speed required for an object to reach infinity (i.e. escape from the earth).

G: Universal Gravitational Constant (Value of G = 6.67 × 10^{-11} Newtons kg^{-2 }m^{2})

M_{E}: Mass of the Earth

R_{E}: Radius of the Earth

Another Formula For Escape Velocity (Earth):

v_{minimum} = (2gR_{E})^{1/2}

g: Acceleration due to gravity

Rest symbols have their usual meaning.

Some questions on Escape Velocity:

Question: What is the SI unit of Escape Speed?

Answer: The Escape Velocity or Escape Speed of an object on the Earth is around 11.2 km/s.

Question: Determine the escape velocity of a planet if its radius is 7000 Km and mass is 107 kg.

Answer:

We know that vminimum = (2GM/R)^{½}

Here,

G = 6.67 × 10^{-11} Newtons kg^{-2 }m^{2}

M = 10^{7} kg.

R = 7000 km = 7000 x 1000 = 7 x 10^{6}.

By putting these values in the formula you can calculate the Escape Velocity of the object.

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