What speed do satellites orbit at?

The key point to recognise here is that an object undergoing a circular orbit around the Earth is undergoing circular motion. Circular motion is caused by a centripetal force (acting towards the centre of the circle), described by:

F= msatellitev2/r   (eq 1)

In the case of an orbit, the force acting towards the centre is due to the gravity of the Earth, which is described by Newton's law of universal gravitation:

F= GmEarthmSatellite/r2  (eq 2)

We can now equate these two expressions:

Fc = Fg => msatellitev2/r = GmEarthmSatellite/r2  (eq 3)

Now me can rearrange to make v the subject of the equation:

v = sqrt(GmEarth/r)   (eq 4)

This is the speed of a satellite in a circular orbit around the Earth. Note that v is proportional to 1/sqrt(r) and that the mass of the satellite has cancelled out.

RM
Answered by Ryan M. Physics tutor

3633 Views

See similar Physics A Level tutors

Related Physics A Level answers

All answers ▸

How can we explain the standing waves on a string?


An infared wave has a wavelength of 1.5 x10^–6 m. The speed of this wave is 2.2 × 10^8 m/s. Calculate the frequency of the wave. Give your answer in standard form and to 2 significant figures.


A bullet is fired horizontally from a gun at a height of 1.5m at 280m/s. Calculate the time taken for it to hit the ground. A second bullet is fired from an adjacent gun at 370m/s. Calculate the distance it travel before the first bullet hits the ground.


Derive an expression for wave speed in terms of wavelength and frequency.


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning