Question:

A body of weight 72 N moves from the surface of earth at a height half of the radius of earth, then gravitational force exerted on it will be

Updated On: Mar 14, 2024
  • 36 N
  • 32 N
  • 144 N
  • 50 N
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The Correct Option is B

Solution and Explanation

$ F_{surface } = G \frac{Mm}{ {R_e}^2}$
$ F_{R_c /2} = G \frac{ Mm}{ (R_e + R_e /2)^2} =\frac{4}{9} \times F_{surface } = \frac{4}{9}\times 72= 32\, N $.
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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].