# E-Fields - trajectory

1. Jan 27, 2010

### jasper10

1. The problem statement, all variables and given/known data

Hello, I have a physics exam on friday. My teacher said one of the questions would be on the TRAJECTORY (of an electron) IN AN E-FIELD. he told us to remember than tanß = sinß / cosß

we haven't used tan, sin or cos during class work. I was hoping someone could give me a clue to what he means.

Thanks

2. Jan 27, 2010

### dacruick

he means that you will need to use tan(beta)

3. Jan 27, 2010

### jasper10

yes i know he will give us some form of equation or something to do with tanß
but how is this related to the trajectory in an e field?

4. Jan 27, 2010

### dacruick

say a uniform electric field points in the x direction. but the electron enters the E field at a certain speed 30 degrees above the direction of the E field, then you are going to have initial components of velocities that involve sine and cosine

5. Jan 28, 2010

### jasper10

So would the equations be:

v = ucosß + at
v^2 = (ucosß)^2 + 2as
s = (ucosß x t ) + .5at^2
?