Practice question

Given: A body weighs 49 N on Earth’s surface. What is its weight at a height h = R_E/4 ? ( g = 9.8 m/s², R_E = 6.4 × 10⁶ m ) These values define the system as per NCERT data. Formula: g(h) = g/(1 + h/R_E)². This is the standard NCERT relation for this phenomenon. Substitution & Calculation: h = R_E/4, 1 + h/R_E = 1 + 1/4 = 5/4 . g(h) = 9.8/(5/4)² = 9.8/25/16 = 9.8 × 16/25 = 6.272 m/s² . Mass: m = 49/9.8 = 5 kg . Weight: W = 5 × 6.272 approx 31.36 N . Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s², 10⁻⁵ are properly used as per NCERT.