Intuitive explanation of why work done by tension is 0?

Click For Summary
SUMMARY

The discussion centers on the concept of work done by tension in a system involving two masses and a pulley. The mathematical derivation shows that the tension force, when analyzed through the equations T-mg=ma and Mg-T=Ma, results in a net work done of zero due to equal and opposite displacements. The intuitive explanation likens the scenario to a tug-of-war, where equal forces and displacements cancel each other out, leading to no net work being performed by the tension in the rope.

PREREQUISITES
  • Understanding of Newton's laws of motion
  • Familiarity with the concept of work in physics
  • Basic knowledge of force and displacement vectors
  • Ability to perform algebraic manipulations and solve equations
NEXT STEPS
  • Study the principles of work and energy in classical mechanics
  • Learn about tension forces in different mechanical systems
  • Explore the concept of equilibrium in physics
  • Investigate the use of integrals in calculating work done by variable forces
USEFUL FOR

Students of physics, educators explaining mechanical concepts, and anyone interested in understanding the principles of work and tension in physical systems.

navneet9431
Gold Member
Messages
107
Reaction score
9

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!
 

Attachments

  • IMG_20180821_092520.jpg
    IMG_20180821_092520.jpg
    22.9 KB · Views: 1,381
Physics news on Phys.org
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.
 
  • Like
Likes   Reactions: navneet9431
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.
 

Similar threads

  • · Replies 16 ·
Replies
16
Views
1K
  • · Replies 3 ·
Replies
3
Views
2K
Replies
29
Views
3K
  • · Replies 4 ·
Replies
4
Views
3K
Replies
7
Views
2K
  • · Replies 8 ·
Replies
8
Views
961
  • · Replies 2 ·
Replies
2
Views
846
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 3 ·
Replies
3
Views
3K
Replies
4
Views
3K