Easy problem still wrong answer

  • Thread starter Thread starter melissa_y
  • Start date Start date
Click For Summary

Homework Help Overview

The problem involves calculating the work needed to move a proton between two points with different electric potentials, specifically from +630V to -60.0V.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to apply the work-energy principle using the potential difference and charge of the proton. Some participants question the expected answer and suggest considering the sign of the work based on who is performing it.

Discussion Status

Participants are exploring the implications of the negative sign in the work calculation and discussing the ambiguity of the problem regarding who is doing the work. There is no explicit consensus on the correct interpretation of the signs involved.

Contextual Notes

There is mention of a potential issue with the answer being rejected by an online system, indicating possible constraints or specific requirements in the homework context.

melissa_y
Messages
17
Reaction score
0
How much work is needed to move a proton from a point with a potential of +630V to a point where it is -60.0V?

Ok so wouldn't I just use the equation:

(Va-Vb)=Wba/q
(-60-630)=Wba/(1.6 x 10^-19)
Wba=-1.104 x 10^-16 J
 
Physics news on Phys.org
Your equation looks fine to me. What's the answer you expected?
 
Wba=-1.104 x 10^-16 J

But i keep entering it into the CAPA and it says wrong answer...
 
Try it without the negative sign.

The question is ambiguous, since it doesn't specify who or what is doing the work. If it's the electric field, then the answer is negative. If it's an external force, the answer is positive.
 
haha i love problems that are so simple yet you don't get an answer. Makes me start pounding on walls. Something simple has obviously gone unnoticed or like someone said, a negative sign is probably missing. Those negative signs piss me off to no end. Everytime i learn something where I am told the answer is always positive, i go to church for 40 hours straight to thank god for all the good he has done in the world such as the current subject i was just taught.

I truly hate negatives...
 

Similar threads

Replies
5
Views
8K
Replies
13
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 2 ·
Replies
2
Views
3K
Replies
8
Views
5K
  • · Replies 2 ·
Replies
2
Views
6K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 1 ·
Replies
1
Views
5K
Replies
34
Views
2K
  • · Replies 2 ·
Replies
2
Views
1K