# Escape Velocity Formula

The escape velocity is the minimum velocity required to leave a planet or moon. For a rocket or other object to leave a planet, it must overcome the pull of gravity. The formula for escape velocity contains a constant, *G*, which is called the "universal gravitational constant". Its value is . The unit for escape velocity is meters per second (*m/s*).

escape velocity (*m/s*)

*G* = universal gravitational constant ()

*M* = mass of the planet or moon (*kg*)

*R* = radius of the planet or moon (*m*)

Escape Velocity Formula Questions:

1) The radius of Earth is 6.38x10^{6 } *m*, and the mass of the Earth is 5.98x10^{24 } *kg*. What is the escape velocity from Earth?

Answer: The escape velocity from Earth can be found using the formula:

11184 *m/s*

The escape velocity from Earth is 11 184 *m/s*, or approximately 11.2*km/s*.

2) To leave the moon, the Apollo astronauts had to take off in the lunar module, and reach the escape velocity of the moon. The radius of the moon is 1.74x10^{6} *m*, and the mass of the moon is 7.35x10^{22} *kg*. What velocity did Neil Armstrong and Buzz Aldrin in the lunar module have to reach to leave the moon?

Answer: The escape velocity from the moon can be found using the formula:

2374 *m/s*

The escape velocity from the moon is 2374 *m/s*, or approximately 2.37 *km/s*.

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