Calculating Velocity from Kinetic Energy: Solving for v in the r=mv/qb Formula

[baylorbelle]

A proton with a kinetic energy of 4.6×10−16 J moves perpendicular to a magnetic field of 0.26 T. What is the radius of its circular path?


I know the formula is r=mv/qb. the only thing not given is v. So my question is how do I get v from Joules? I know 1 Joule=1N/m, and that N=ma, but I don't know how to get velocity from that. Any help on that part would be greatly appreciated : )

 

[Doc Al]

What's the definition of kinetic energy?

 

[baylorbelle]

1/2 mv^2

 

[Doc Al]

1/2 mv^2

There you go. Now you can solve for v using the given information. (You may have to look up the mass of a proton.)

 

[baylorbelle]

thanks!