Gravitation - Result Question 22

22. A body weighs 72N on the surface of the earth. What is the gravitational force on it due to earth at a height equal to half the radius of the earth from the surface?

[2000]

(a) 32N

(b) 28N

(c) 16N

(d) 72N

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Answer:

Correct Answer: 22. (a)

Solution:

  1. (a) mg=72N (body weight on the surface)

g=GMR2

At a height H=R2,

g=GM(R+R2)2=4GM9R2

Body weight at height H=R2,

mg=m×49(GMR2)=m×49×g=49mg=49×72=32N



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