Trajectory of a proton as it moves between the plates

  • #1
Cicicicici
15
0

Homework Statement


Screen Shot 2018-05-25 at 1.44.19 pm.png


Homework Equations


What makes the shape circular/ parabolic?
what determines the direction?

The Attempt at a Solution


Because the furthermost plate is positive, the proton would be repelled towards the screen, so i or iii. How do I know the shape?
 

Attachments

  • Screen Shot 2018-05-25 at 1.44.19 pm.png
    Screen Shot 2018-05-25 at 1.44.19 pm.png
    31.8 KB · Views: 767

Answers and Replies

  • #2
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
2021 Award
12,301
5,391
How do I know the shape?
What kind of acceleration generates circular motion? What about parabolic motion? Which do you have here?
 
  • #3
Cicicicici
15
0
What kind of acceleration generates circular motion? What about parabolic motion? Which do you have here?
Hi, is it because the proton is accelerating along the field lines not perpendicular to them? so it is a parabolic motion?
 
  • #4
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
2021 Award
12,301
5,391
You provided a valid argument for parabolic motion. To answer with certainty, you need to provide an argument for excluding circular motion. What is that argument?
 
  • #5
Cicicicici
15
0
You provided a valid argument for parabolic motion. To answer with certainty, you need to provide an argument for excluding circular motion. What is that argument?
ummmm... I'm not sure. Has it got something to do with the proton reaching terminal velocity before the plates?
 
  • #6
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
2021 Award
12,301
5,391
ummmm... I'm not sure. Has it got something to do with the proton reaching terminal velocity before the plates?
Nope. That's there to indicate that the vertical component of the velocity is constant. What kind of acceleration does an object in a circular path have? What's the difference between that kind of acceleration and the kind you have here?
 
  • #7
Cicicicici
15
0
Nope. That's there to indicate that the vertical component of the velocity is constant. What kind of acceleration does an object in a circular path have? What's the difference between that kind of acceleration and the kind you have here?
Centripetal acceleration? And this one is just uniform?
 
  • #8
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
2021 Award
12,301
5,391
Correct on both accounts. Centripetal acceleration changes direction to stay perpendicular to the velocity. Here the direction of the acceleration is fixed in space and is perpendicualr to the velocity instantaneously only when the proton enters the plate region.
 
  • #9
Cicicicici
15
0
Correct on both accounts. Centripetal acceleration changes direction to stay perpendicular to the velocity. Here the direction of the acceleration is fixed in space and is perpendicualr to the velocity instantaneously only when the proton enters the plate region.
I am a bit confused - isn't the acceleration zero here? (because it is at terminal velocity?)
 
  • #10
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
2021 Award
12,301
5,391
How many different forces act on the proton?
 
  • #11
Cicicicici
15
0
How many different forces act on the proton?
gravity and repulsion from the positive plate?
 
  • #12
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
2021 Award
12,301
5,391
And some kind of air resistance otherwise the proton would not have reached terminal velocity before entering the plate area. The acceleration is zero before the proton enters the plate area. When it enters the plate area, the acceleration is no longer zero.
 
  • #13
Cicicicici
15
0
And some kind of air resistance otherwise the proton would not have reached terminal velocity before entering the plate area. The acceleration is zero before the proton enters the plate area. When it enters the plate area, the acceleration is no longer zero.
Ah! right. Thank you!
 

Suggested for: Trajectory of a proton as it moves between the plates

Replies
9
Views
340
Replies
4
Views
499
Replies
3
Views
337
  • Last Post
Replies
3
Views
277
Replies
28
Views
1K
Replies
1
Views
192
  • Last Post
Replies
4
Views
2K
Top