JEE Main 2025 Jan 28 Shift 2, Physics Q11: Gravitational Potential, Potential Energy And Work Done

JEE Main2025Jan 28, Shift 2Physics

Earth has mass 8 times and radius 2 times that of a planet. If the escape velocity from the earth is $11.2$ km/s, the escape velocity in km/s from the planet will be :

A
$11.2$
B
$5.6$
C
$2.8$
D
$8.4$

Solution

Escape speed: $v_{e} = \frac{2 GM}{R}$ .

$\frac{v _{e, planet}}{v _{e, earth}} = \frac{M _{p}}{M _{e}} \cdot \frac{R _{e}}{R _{p}} = \frac{1}{8} \cdot 2 = \frac{1}{4} = \frac{1}{2}$ .

$∴ v_{e, planet} = \frac{11.2}{2} = 5.6$ km/s.

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JEE Main 2025 Jan 28 Shift 2, Physics Q11: Gravitational Potential, Potential Energy And Work Done

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