Opposing forces but opposite travel = no work?

Click For Summary

Discussion Overview

The discussion revolves around the concept of work in physics, particularly in the context of two objects experiencing opposing forces while traveling in opposite directions. Participants explore the definitions and implications of work, displacement, and the conditions under which work is done or not done.

Discussion Character

  • Debate/contested, Conceptual clarification, Technical explanation

Main Points Raised

  • One participant questions whether two objects with opposing forces can travel in opposite directions without doing work, indicating a basic understanding of physics.
  • Another participant explains that work is defined as a force applied over a net distance (displacement), suggesting that if two boxes are pushed to their starting positions, the overall work done is zero.
  • A different participant challenges this explanation, asserting that work is a force applied over a distance rather than a net distance, emphasizing the importance of considering non-conservative forces like friction.
  • Another participant states that both boxes in the diagram are doing work, implying that the direction of forces does not negate the work done.
  • One participant raises a question about the mechanical possibility of stopping both boxes from doing work, indicating an interest in practical applications of the concepts discussed.

Areas of Agreement / Disagreement

Participants express differing views on the definition of work and the conditions under which it is done. There is no consensus on the interpretation of work in the context presented, and multiple competing views remain unresolved.

Contextual Notes

The discussion highlights potential ambiguities in the definitions of work and displacement, particularly in relation to conservative and non-conservative forces. The implications of friction and the mechanical aspects of the scenario are also noted but not fully resolved.

CountFleet
Messages
8
Reaction score
0
Hi, This is something I was wondering about. Can two objects with opposing forces travel in opposite directions without any work(minus friction)? I made a drawing in pdf format to demonstrate what I'm trying to say. My understanding of physics is pretty elementary so I apologize if this is a stupid question.
 

Attachments

Last edited:
Physics news on Phys.org
Work is equal to a force applied over a net distance (aka displacement) . Net distance is the difference between your starting and ending point. So if you push a box from point A to point B, and then push it back from point B to point A, no work will be done.

In your diagram, for part 1, it looks like the first box is being pushed to the right by a force pointed to the right, so positive work is being done on that box. The second box is being pushed to the left by a force pointed to the left, so the work being done on that box is also positive. It doesn't matter if the boxes are going in different directions, they are both being moved with positive work.

however, in your second part, it looks like you push the boxes back to their starting positions, so the overall work for the first and second part would be zero since the boxes don't have a change in displacement.
 
Trexman89 said:
Work is equal to a force applied over a net distance (aka displacement) . Net distance is the difference between your starting and ending point. So if you push a box from point A to point B, and then push it back from point B to point A, no work will be done.

This is incorrect. Work is a force applied over a distance, NOT a force applied over a net distance or displacement. If your force is conservative then the difference is moot, but in the case of friction where the force is not conservative then the difference is very important.
 
In your diagram both boxes are DOING work.
 
I was wondering if it was mechanically possible to stop both boxes from doing work?
 

Similar threads

High School Are frictional forces action forces or reaction forces?
  • · Replies 14 ·
Replies
14
Views
2K
High School Pressure through a curved hose - expected results?
  • · Replies 15 ·
Replies
15
Views
3K
Undergrad Is it accurate to say work is motion against an opposing force?
  • · Replies 75 ·
3
Replies
75
Views
5K
High School Work Done By Conservative Forces
  • · Replies 1 ·
Replies
1
Views
2K
High School How does an object gain potential energy?
  • · Replies 54 ·
2
Replies
54
Views
7K
High School Understanding Newton's Third Law and the Net Force on Objects
  • · Replies 19 ·
Replies
19
Views
2K
High School Work done when moving an object
  • · Replies 7 ·
Replies
7
Views
1K
High School Box being pulled up a slope with friction
  • · Replies 3 ·
Replies
3
Views
2K
High School Why does friction decrease with repeated force application?
  • · Replies 11 ·
Replies
11
Views
2K
High School Newton's third law (equal and opposite force)
  • · Replies 40 ·
2
Replies
40
Views
4K