How Do You Calculate the Rest Energy of a Ball?

[Westin]

Homework Statement

A ball whose mass is 8kg travels at a velocity [PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char68.png22,79,6[PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char69.pngm[PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmmi10/alpha/144/char3D.pngs. What is the rest energy of the ball?[/B]

Homework Equations

K=1/2 mv^2[/B]

The Attempt at a Solution

K=1/2 (8) v^2

Im not sure what to do with velocity since its in vector form, I tried taking the magnitude of it but that was incorrect.[/B]

 

[SteamKing]

Homework Statement

A ball whose mass is 8kg travels at a velocity [PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char68.png22,79,6[PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char69.pngm[PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmmi10/alpha/144/char3D.pngs. What is the rest energy of the ball?[/B]

Homework Equations

K=1/2 mv^2[/B]

The Attempt at a Solution

K=1/2 (8) v^2

Im not sure what to do with velocity since its in vector form, I tried taking the magnitude of it but that was incorrect.[/B]

The problem is asking for the 'rest energy' of the ball. I don't think you need to know the velocity of the ball in order to calculate its rest energy.

 

[haruspex]

The problem is asking for the 'rest energy' of the ball. I don't think you need to know the velocity of the ball in order to calculate its rest energy.

Unless the mass given is based on the speed given, but it's a speed so subluminal the difference will be minute.