Escape Velocity: Formula, Definition, Questions & More

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.

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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 m²)

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 m²

M = 10⁷ kg.

R =  7000 km = 7000 x 1000 = 7 x 10⁶.

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