Find Magnetic Force: Electron & Proton

[Medtner]

Homework Statement

An electron that has a velocity with x component 2.1 × 106 m/s and y component 3.1 × 106 m/s moves through a uniform magnetic field with x component 0.035 T and y component -0.16 T. (a) Find the magnitude of the magnetic force on the electron. (b) Repeat your calculation for a proton having the same velocity.

Homework Equations

Fb=qVxB
q(VxBy-ByBx)

The Attempt at a Solution

I did the work, got an answer for part A which is 7.112e-14
Did the exact same procedure for part B and arrived at -7.112e-14, but the homework website is telling me it's wrong?! Not sure what my error is...

 

[TSny]

The question asks for the magnitude of the force.

 

[Medtner]

*facepalm*

Silly me, I should read questions more carefully. Forgot to absolute value on both parts, only with a it work out by luck! Thanks.

 

[TSny]

OK, good.