The weight of a body on the surface of the earth is 100 N. The gravitational force on it when taken at a height, from the surface of earth, equal to one-fourth the radius of the earth is:
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The weight of a body on the surface of the earth is 100 N. The gravitational force on it when taken at a height, from the surface of earth, equal to one-fourth the radius of the earth is:

G1 Physics · Accepted Answer

Step 1: Outside a spherical Earth/planet, g(r)=GM/r²; near the surface gh/g≈(R/(R+h))²≈1-2h/R. Inside a uniform sphere g varies linearly with distance from the centre. Step 2: Use the relation appropriate to the stated height/depth. Step 3: Simplify. Final: B: 64 N.