Practice question
Question
What is the kinetic energy of a 300kg satellite at 5RE from Earth’s center? (ME\=6×1024kg,RE\=6.4×106m,G\=6.67×10−11N m2/kg2)
Explanation
K = GMEm2r. r = 5RE = 3.2×107m. K = 6.67×10−11×6×1024×3002×3.2×107. K = 1.201×10176.4×107≈1.88×109J. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 1.9 × 10⁹ J. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.