Acceleration of electron?

1. Mar 5, 2008

j91621

Acceleration of electron??

Please atleast help me by explaining what I should do. I have found velocity by setting kenetic energy to .5mv^2 and used the mass of an electron for the mass and found that velocity is 6.182. Next i set mass x gravity=qvbsin(theta) and apparently whatever i did from here is wrong. Thanks for your help.

The electrons in the beam of a television tube have a kinetic energy of 2.10 10-15 J. Initially, the electrons move horizontally from west to east. The vertical component of the earth's magnetic field points down, toward the surface of the earth, and has a magnitude of 1.00 10-5 T.
What is the acceleration of an electron in part (a)?

2. Mar 5, 2008

Oxymuon

The electrons are initially moving perpendicularly to the field - so sin(theta) = 1. Is that what you did and you still got the wrong answer?

3. Mar 5, 2008

Oxymuon

j916 - I didn't realize what you were doing the first time. There are two forces at play here - the magnetic and the graviational - what you want to do is set the total force equal to the combination of both of them, and then find the acceleration from that total force.