Short Question Answers

Q1. What is escape velocity? Obtain an expression for it.

Ans. Definition : The minimum velocity required for an object to escape from the gravitational. influence of the planet is called Escape Velocity

Expression for escape velocity :Consider a body of mass m thrown with a velocity $V_{e}$ from a planet of mass $M$ and radius $R$.

Kinetic energy of theobject is equal to potential energy and it is in opposite direction.
$$\begin{gathered}
\frac{1}{2}mV_{e}^{2}=-\left(-\frac{GMm}{R}\right) \\
V_{e}=\sqrt{\frac{2GM}{R}} \\
V_{e}=\sqrt{2gR} 
\end{gathered}$$

Earth escape velocity $V_{e}= 11. 2$ $km/ s$

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