Condition for Free Fall around Earth

Initializing live version
Download to Desktop

Requires a Wolfram Notebook System

Interact on desktop, mobile and cloud with the free Wolfram Player or other Wolfram Language products.

For a body to stay in orbit around Earth, it must travel tangentially (magenta arrow) with a velocity that lets the body fall a radial distance due to the force of gravity (black arrow) in such a way that it follows the curvature of Earth (yellow arrow). The resultant displacement can be represented as the sum of both motions (blue arrow). As an example, astronauts inside a space shuttle appear to be floating in zero gravity with an absence of gravity, but actually they are continuously falling around Earth.


It is easy to calculate that near Earth's surface a body must travel tangentially at about 7.9 kilometers per second to stay in orbit.


Contributed by: Enrique Zeleny (March 2011)
Open content licensed under CC BY-NC-SA




Feedback (field required)
Email (field required) Name
Occupation Organization
Note: Your message & contact information may be shared with the author of any specific Demonstration for which you give feedback.