Question:

A planet in a distant solar system is 10 times more massive than the earth and its radius is 10 times smaller. Given that the escape velocity from the earth is ${11 \, km \, s^{-1}}$, the escape velocity from the surface of the planet would be

Updated On: Jun 7, 2022
  • ${0.11 \, km \, s^{-1}}$
  • ${1.1 \, km \, s^{-1}}$
  • ${11 \, km \, s^{-1}}$
  • ${110 \, km \, s^{-1}}$
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The Correct Option is D

Solution and Explanation

Escape velocity from the surface of the earth is
$\upsilon_e = \sqrt{\frac{2GM}{R}}$
$\upsilon_e = 11 \, km \, s^{-1}$
Mass of the planet = $10M$.
Radius of the planet = $R/10$.
$ \therefore \, \upsilon_p = \sqrt{\frac{2GM \times 10}{R/10}} = 10 \upsilon_e = 10 \times 11$
$ = { 110 \, km \, s^{-1}}$
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Concepts Used:

Gravitation

In mechanics, the universal force of attraction acting between all matter is known as Gravity, also called gravitation, . It is the weakest known force in nature.

Newton’s Law of Gravitation

According to Newton’s law of gravitation, “Every particle in the universe attracts every other particle with a force whose magnitude is,

  • F ∝ (M1M2) . . . . (1)
  • (F ∝ 1/r2) . . . . (2)

On combining equations (1) and (2) we get,

F ∝ M1M2/r2

F = G × [M1M2]/r2 . . . . (7)

Or, f(r) = GM1M2/r2

The dimension formula of G is [M-1L3T-2].