Practice question

Distance to 18kg: 18−8 = 10m. U = −Gm1r1−Gm2r2. U = −6.67×10−11(98+1810). U = −6.67×10−11(1.125+1.8)≈−1.95×10−10J/kg. As per NCERT, applying relevant law/formula with correct units and sign convention leads to -1.9 × 10⁻¹⁰ J/kg. This satisfies dimensional consistency and physical conditions given, so option A is scientifically correct.