Calculate the force of Earth's gravity on a spacecraft 12,800 km (2 Earth radii) above the Earth's surface if its mass is 1250 kg .

Answer 1

Kepler's third law provides an equation for the force of gravity: Fg = Gm₁m₂ / r². G is the gravitational constant (6.6743 × 10^-11 m³kg^-1s^-2), m₁ is the mass of the Earth (5.972 × 10²⁴), m₂ is the mass of the spacecraft (1250 kg), and r is the distance between the center of the earth and spacecraft (radius of the earth + distance between the earth's surface and the spacecraft = 12,800 + 6,400 km = 19,200 km, but we need it in meters, so 19,200,000 m).

Plugging into the equation, we get an answer of 1351.553 N.