Velocity of a Proton in a Capacitor

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Homework Help Overview

The problem involves a proton moving through a parallel-plate capacitor, where it is fired horizontally with a specified speed and enters the capacitor at a certain height above the lower plate. The electric field within the capacitor is directed downwards, and the task is to determine where the proton strikes the lower plate.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants discuss the setup of kinematics tables for both horizontal and vertical motion, noting known values such as initial velocity and acceleration. Questions arise regarding the direction of acceleration due to the electric field and its implications for the kinematics analysis.

Discussion Status

Participants are actively engaging with the problem, with one noting a realization about the direction of acceleration in relation to the electric field. There is an acknowledgment of the horizontal acceleration being zero, indicating a productive direction in the discussion.

Contextual Notes

Participants are working with specific values for acceleration and voltage, and there is a reference to previous questions related to the problem, suggesting a broader context of inquiry.

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 (separate for horizontal and vertical):

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

Known for vertical: 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 (separate for horizontal and vertical):

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

Known for vertical: 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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