Practice question
Question
A satellite of mass 500kg orbits Earth at 2RE from the center. What is its kinetic energy? (ME\=6×1024kg,RE\=6.4×106m,G\=6.67×10−11N m2/kg2)
Explanation
K = GMEm2r. r = 2RE = 2×6.4×106 = 1.28×107m. K = 6.67×10−11×6×1024×5002×1.28×107. K = 2.001×10172.56×107≈7.82×109J. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 7.8 × 10⁹ J. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.