A body weighs 48 N at Earth’s surface. What gravitational force acts on it at height h = R/3 above the surface (R is Earth’s radius)?
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Question

A body weighs 48 N at Earth’s surface. What gravitational force acts on it at height h = R/3 above the surface (R is Earth’s radius)?

G1 Physics · Accepted Answer

Step 1: Gravitational force at distance r from Earth’s centre varies as 1/r². Step 2: At the surface, r₀ = R and force W₀ = 48 N. Step 3: At height h = R/3, the new centre distance is R + h = 4R/3. Step 4: W = W₀[R/(R+h)]² = 48(3/4)² = 48 × 9/16 = 27 N. Final answer: 27 N, Option B.