Question

The international space station orbits the earth at about 200km above the earth's surface. An astronaut in the space station experiences "micro gravity". Use newtons law of gravity to determine the astronauts actual weigh in orbit. why is this considered "micro gravity"

Answer 1

R = radius of earth = 6.37 x 10⁶ m

M = mass of earth = 5.98 x 10²⁴ kg

h = height above the surface of earth = 200 km = 0.2 x 10⁶ m

m = mass of astronaut

W = actual weight in orbit

Actual weight in orbit is same as the force of gravitation between earth and astronaut, hence

W = G Mm/(R + h)²

W = (6.67 x 10^-11) (5.98 x 10²⁴) m/((6.37 x 10⁶) + (0.2 x 10⁶))²

W = 9.24 m

this is called micro gravity since 90% of earth's gravity reach the astronaut at international space station