Velocity of a Proton in a Capacitor

AI Thread Summary
A proton is fired horizontally at 1.1 x 10^6 m/s through a parallel-plate capacitor with a downward electric field of 1.3 x 10^5 V/m. The proton enters the capacitor 18.6 mm above the lower plate, and the acceleration due to the electric field is calculated to be 1.245 x 10^13 m/s² downward. The horizontal motion remains unaffected by the electric field, while vertical motion is influenced by the downward acceleration. The discussion emphasizes the importance of correctly interpreting the direction of acceleration in kinematics calculations. The participants express gratitude for clarifications that enhance their understanding of the problem.
Phoenixtears
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Homework Statement



A proton is fired horizontally with a speed of 1.1 106 m/s through the parallel-plate capacitor shown in Figure P34.37. The capacitor's electric field is = (1.3 105 V/m, down) and the distance between the plates is 31 millimeter.
(Image Attached)


The proton entered the capacitor gap 18.6 milli-meters above the lower plate. Where doe the proton strike the lower plate?

Measured in meters from the front edge of the lower plate.

Homework Equations



Kinematics Equations

The Attempt at a Solution



There were other questions on this problem that I already solved for. So here are other things that I know:

The magnitude of the acceleration= 1.245E13 m/s/s

Voltage difference= 4030 V


Now I've set up a kinematics table (seperate for horizontal and verticle):

Known for horizontal: Initial V= 1.1E6; A= 1.245E13
Uknown: distance, final velocity, time

Known for verticle: x= .0186 meters; Initial v= 0
Uknown: final velocity, acceleration, time


Any suggestions? I've no idea where to go from here.

Thanks in advance!

~Phoenix
 

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Hi Phoenixtears,

Phoenixtears said:

Homework Statement



A proton is fired horizontally with a speed of 1.1 106 m/s through the parallel-plate capacitor shown in Figure P34.37. The capacitor's electric field is = (1.3 105 V/m, down) and the distance between the plates is 31 millimeter.
(Image Attached)


The proton entered the capacitor gap 18.6 milli-meters above the lower plate. Where doe the proton strike the lower plate?

Measured in meters from the front edge of the lower plate.

Homework Equations



Kinematics Equations

The Attempt at a Solution



There were other questions on this problem that I already solved for. So here are other things that I know:

The magnitude of the acceleration= 1.245E13 m/s/s

Since the electric field is downwards, what is the direction of this acceleration? I think the answer for this will change your kinematics table below.


Voltage difference= 4030 V


Now I've set up a kinematics table (seperate for horizontal and verticle):

Known for horizontal: Initial V= 1.1E6; A= 1.245E13
Uknown: distance, final velocity, time

Known for verticle: x= .0186 meters; Initial v= 0
Uknown: final velocity, acceleration, time


Any suggestions? I've no idea where to go from here.

Thanks in advance!

~Phoenix
 


Aha! I see. That makes so much more sense.

Becasue the field is down, the acceleration is also down. Then the horizonatal acceleration is 0 (I should have listened to my sister :-P). Thank you so much!
 


Phoenixtears said:
Aha! I see. That makes so much more sense.

Becasue the field is down, the acceleration is also down. Then the horizonatal acceleration is 0 (I should have listened to my sister :-P). Thank you so much!

Sure, glad to help!
 
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