Question

Why do different planets have different escape speeds?

Answer 1

Hint: We know that when we throw a ball or launch a satellite we have to give them some speed. The ball thrown upwards comes back this is due to the gravitational pull of the Earth. This means we need a very high speed if we want the ball not to come down again. So, we need a speed with which if we throw the ball it will never come back on Earth. Escape velocity is the minimum speed with which if we throw the object it will leave the planets or massive objects gravitational field.

Complete step by step solution:
The following is the formula to calculate the escape velocity of the planet.
${v_{escape}} = \sqrt {\dfrac{{2GM}}{R}} $
Here, $R$ is the radius of the planet, $G$ is the universal gravitational constant,$M$ is the mass of the planet, and ${v_{escape}}$ is the escape velocity of the planet.
From the formula, we come to know that the escape velocity depends on the mass and radius of the planet.
Therefore, the escape velocity of different planets is different.

Note:
The escape velocity of Earth is $11.2km/s$ and that of the Moon is $2.38km/s$.
Most of the satellites do not reach the escape velocity of the earth. So, when a satellite sent to space enters space but is not able to achieve the escape velocity then it will enter the orbit around the earth.
Escape velocity does not depend on the direction, hence we call it escape speed. Whatever be the direction, if we were given an object the speed equal to the escape velocity of the Earth it will leave the earth’s gravitational field.