Mass of Particle in 0.200T Magnetic Field

[taylor.simon]

Homework Statement

what is the mass of a particle which travels in a circular path with a kinetic energy of 3.2 x 10 ^-19 J moving perpendicular to a 0.200t magnetic field if it has a charge of 1.6 x10 ^-19 C and the path radius is 10 cm

Homework Equations

ke= 1/2 mv^2

mv^2/r = qvB

r = mv^2/qvB = mv/qB

mv = qBr

The Attempt at a Solution

mv =qbr
mv = 1.6 x10 ^-19 C x 0.200 T x 0.1 M
mv = 3.2x 10 ^-21

i can't figure out how to separate the mass and velocity using ke=1/2mv^2
any help is much appreciated

 

[Delphi51]

Write ke=1/2mv^2 as ke = ½(mv)v and replace the mv with value you found. Since you know the value of ke, you can then easily find v.