Position,velocity, speed, direction of travel of an electron

  • #1

Homework Statement


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 hat bold = vii hat bold. 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 = 1.93 multiplied by 10^7 m/s, ax = 8.88 multiplied by 10^14 m/s2, and ay = 1.48 multiplied by 10^15 m/s2, determine the following, at x = d = 0.0100 m.
a)Find the position of the electron
b) the velocity of the electron
c) the speed of the electron
d)the direction of travel of the electron



Homework Equations


For a, i tried using the equation Yf=1/2ayt^2
but the answer was wrong and I dont know if i used the wrong equation/numbers
b-d i dont know where to start

The Attempt at a Solution


I used above equation and got -0.000235
 
Last edited:

Answers and Replies

  • #2
gneill
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Start by concentrating on the motion in the x-direction since you're given the distance of travel. It may be easier to determine the x-direction speed first, then find the time of travel.

So, what other equation of motion do you know that relates the initial and final speeds with acceleration and distance?
 
  • #3
Start by concentrating on the motion in the x-direction since you're given the distance of travel. It may be easier to determine the x-direction speed first, then find the time of travel.

So, what other equation of motion do you know that relates the initial and final speeds with acceleration and distance?
Wouldnt that be Vxf^2=Vxi^2+2ax(xf-xi)?
 
  • #4
gneill
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Wouldnt that be Vxf^2=Vxi^2+2ax(xf-xi)?
That would be the one. What do you get for the final speed of the electron in the x-direction?
 
  • #5
That would be the one. What do you get for the final speed of the electron in the x-direction?
Well if I did everything right, I got 1.93x10^7 m/s
????
 
  • #6
wait but thats the same as Vi
 
  • #7
gneill
Mentor
20,913
2,860
Well if I did everything right, I got 1.93x10^7 m/s
????
wait but thats the same as Vi
Yes, so that can't be right (unless the acceleration is insignificant, which it isn't in this case).

Perhaps you should show the work in detail.
 

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