Intuitive explanation of why work done by tension is 0?

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Homework Help Overview

The discussion revolves around understanding why the net work done by tension in a system, such as a pulley or a tug-of-war scenario, is considered to be zero. Participants are seeking an intuitive explanation for this concept within the context of physics.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the relationship between force and displacement, questioning how equal and opposite forces in scenarios like tug-of-war lead to zero net work. They also consider the implications of movement in the system, such as when one team moves forward while the other moves backward.

Discussion Status

The discussion is ongoing with various interpretations being explored. Some participants have provided mathematical reasoning related to work done by tension, while others are focused on intuitive explanations. There is no explicit consensus yet, but several lines of reasoning are being examined.

Contextual Notes

Participants are discussing the assumptions related to the forces and displacements involved in the scenarios presented, particularly in relation to the behavior of the pulley and the tug-of-war analogy.

navneet9431
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Homework Statement


IMG_20180821_092520.jpg


Homework Equations


Work Done=Force*Displacement in the direction of the force

The Attempt at a Solution


I tried to solve the problem this way,
I wrote these equations for the two masses,
T-mg=ma...(i)
Mg-T=Ma...(ii)
From (i)&(ii), T=[M(g-a)+m(a+g)]/2
and then I would multiply them with the displacement to get the net work done 0.
So this is how I solved it mathematically.
Can you please provide an intuitive explanation of why the net work done by tension would be zero?
I will be thankful for help!
 

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navneet9431 said:
Can you please provide an intuitive explanation of why the net work done by tension would be zero?
Suppose you have two tug-of-war teams pulling on a rope and both teams are at a standstill. What work is being done?
 
But the pulley is not standstill.right?
phinds said:
Suppose you have two tug-of-war teams pulling on a rope and both teams are at a standstill. What work is being done?
 
navneet9431 said:
But the pulley is not standstill.right?
OK, suppose one team walks forward at 2mph and the other team walks backwards at 2mph, it which case the tension is unchanged. How much work does the tension do?
 
navneet9431 said:
provide an intuitive explanation of why the net work done by tension would be zero?
For a constant force, work = force times displacement.
In a tug of war, equal and opposite forces, equal displacements. Fd+(-F)d=0.
For the pulley set up in the diagram, equal forces, equal and opposite displacements. F.d+F(-d)=0.
Easy to generalise to variable forces using integrals.
 
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haruspex said:
For a constant force, work = force times displacement.
In a tug of war, equal and opposite forces, equal displacements. Fd+(-F)d=0.
For the pulley set up in the diagram, equal forces, equal and opposite displacements. F.d+F(-d)=0.
Easy to generalise to variable forces using integrals.
Thanks!
It was easy to understand.
 

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