# Displacement of a particle moving on the xy axis?

1. Jan 31, 2014

### JessicaJ283782

As an example of the manipulation of an electron beam, consider an electron traveling away from the origin along the x axis in the xy plane with initial velocity vi= vii. As it passes through the region x = 0 to x = d, the electron experiences acceleration a = axi + ayj, where ax and ay are constants. For the case vi = 1.74 ✕ 10^7 m/s, ax = 7.84 ✕ 10^14 m/s2, and ay = 1.51 ✕ 10^15 m/s2, determine the following, at x = d = 0.0100 m.

(a) the position of the electron (yf=?)

So, I went through, and I used the equation d=vi*t+.5(at^2)

I plugged in: .01=1.74*10^7t+.5(7.84*10^14)t^2

I got the time to be 5.67458*10^-10

Now, I know you have to plug the time into an equation, along with the acceleration of y, but Im confused on which equation to use since you only know acceleration and time for the y coordinates?

(b) the velocity of the electron

So, I used: vf=vi+at

vf(x)=5.67458*10^-10 X 7.84*10^14

and wouldn't you do the same for the y coordinates?

Thank you!

2. Jan 31, 2014

### hjelmgart

a)
So at this point in time, you now need to find the y-coordinate of the electron. You know the acceleration in the y-direction. Can't you find an equations, which you could then use? Perhaps the very same equation, you just used to find the time, just with different parameters?

3. Jan 31, 2014

### RTW69

Actually you know the velocity of the electron in the y-direction it is 0 m/s, therefore v=1.74*10^7i+0j m/s
and a=7.84*10^14i+1.5*10^15j, you have solved for t and you know vi and ai so you can solve for y. You are almost there.