Work done on object vs work done by you

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Homework Help Overview

The discussion revolves around the concepts of work done on an object versus work done by an individual, particularly in the context of physics problems involving forces, mass, and friction. The original poster presents a scenario involving a force exerted on a mass and seeks clarification on how to differentiate between the two types of work.

Discussion Character

  • Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants explore the definitions of work done on an object and work done by an individual, questioning how to calculate each in the context of the provided example. There are attempts to relate work to energy changes, particularly kinetic and heat energy, while some participants suggest examining the total forces involved.

Discussion Status

The discussion is active, with participants offering insights into the calculations needed to differentiate the two types of work. Some guidance has been provided regarding the importance of considering all forces acting on the mass and the implications of energy loss in the process.

Contextual Notes

Participants are working within the constraints of a homework problem, which includes specific values for force, mass, distance, and friction. There is an emphasis on understanding the underlying physics concepts rather than simply calculating answers.

rusty711
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What is the difference between work done on an object and work done by you?

For example, you exert a 100N force pushing a 10kg mass 3.0m across the floor with a coefficient of friction 0.60
1) what is the work done on the mass?
2) what is the work done by you?

For question 1 I think it has to do with a change in kinetic energy, and 2 with kinetic energy and heat energy, but I'm not sure how to solve? Thanks!
 
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Work done by you is manifest as sweat.
 
But how do I solve these? What's the difference
 
You should be able to see the difference by doing the calculation. Start from the equation for work.
What is the total force on the mass? How far does it move?
What is the total force on "you"? How far do "you" move?

Basically: Things doing work lose energy.
I think what they want you to notice is that not all the work done by "you" is done on the mass.
Where else could your energy be going?
 
rusty711 said:
What is the difference between work done on an object and work done by you?

For example, you exert a 100N force pushing a 10kg mass 3.0m across the floor with a coefficient of friction 0.60
1) what is the work done on the mass?
2) what is the work done by you?

For question 1 I think it has to do with a change in kinetic energy, and 2 with kinetic energy and heat energy, but I'm not sure how to solve? Thanks!

The work done on the mass includes the work of all the forces, both yours and the force of friction (the work of the resultant force) which is equal to the change of kinetic energy.
Recall: work is force times displacement. Your work is equal to your force times the displacement of the mass.
 

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