Conceptual Physics

Speed in circular orbit

m = mass of satellite

v = satellite speed

G = gravitational constant

M = mass of body being orbited

r = orbital radius

12.10 - Sample problem: speed of an orbiting satellite

The illustration above shows a satellite in circular orbit 500 km above the Earth’s surface. The Earth’s radius is stated in the variables table.

Variables

What is the strategy?

Determine the satellite’s orbital radius, which is its distance from the center of the body being orbited.

Use the orbital speed equation to determine the satellite’s speed.

Physics principles and equations

The equation for orbital speed is

What is the speed of a satellite in

circular orbit 500 kilometers above

the Earth's surface?

satellite speed v

satellite orbital radius r

satellite height h = 500 km

Earth’s radius rE = 6.38×10^6 m

Earth’s mass ME = 5.97×10^24 kg

gravitational constant G = 6.67×10í^11 N·m^2 /kg^2