- #1

- 292

- 1

## Homework Statement

An electron has an initial velocity of (12.0

**j**+ 15.0

**k**) km/s and a constant acceleration of (2.00x10

^{12}m/s

^{2})

**i**in a region in which uniform electric and magnetic field are present. If

**B**=(400x10

^{-6})

**i**, find the electric field

**E**.

## Homework Equations

[itex]\vec {B}=qVBsin \theta[/itex]

F=ma

## The Attempt at a Solution

Total force on the electon is the sum of the force from the electric field and the force from the magnetic field.

[itex]F_{tot} = F_B + F_E [/itex]

[itex]F_{tot} = qVBsin \theta + qE[/itex]

I don't know how to use the vectors in this notation in the above equations. For instance, if I calculate the total force in the x-direction using [itex]F=ma_x[/itex], I get a number. If I do that in the y-direction, I get zero since there's no acceleration in the y direction. Same for z. However, when breaking up the equation [itex]F=qVBsin\theta[/itex] I don't know how to break up V and B into its components.

(I hate vectors and I hate my book.)