What is the force of gravity acting on a 2000 kg spacecraft when it orbits two Earth radii from the Earth’s center (re = 6380 km)? The mass of the Earth is me=5.98x1024kg.

Answer 1

Gravitational force F_g = G m₁ m₂ / r² = (6.673 x 10^-11) (5.98 x 10²⁴ kg) (2000 kg) / (2 • 6.38 x 10⁶ m)² = 4.90 x 10³ N. Another way would be to calculate the weight with g = 9.8 / 2² = 2.45 m/s² for the field strength at twice the distance, then multiply by the spacecraft's mass.