Uh oh! Wolfram|Alpha doesn't run without JavaScript.
Please enable JavaScript. If you don't know how, you can find instructions
here
.
Once you've done that, refresh this page to start using Wolfram|Alpha.
(1g * c^2) * (1 / sqrt(1 - (.9c)^2 / c^2) - 1)
Natural Language
Math Input
Extended Keyboard
Examples
Upload
Random
