Cannot Lift Piano: Force or Work Not Enough

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Homework Help Overview

The discussion revolves around the physics of lifting a piano, focusing on the concepts of force and work. Participants are exploring the conditions under which lifting a heavy object like a piano is feasible, particularly in the context of human capability without mechanical assistance.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are considering different interpretations of the question, particularly whether the inability to lift the piano is due to insufficient force, insufficient work, or both. There are discussions about the role of mechanical systems, such as pulleys, in performing work and whether these systems change the fundamental problem.

Discussion Status

The conversation is ongoing, with various viewpoints being expressed. Some participants suggest that the question implies a scenario without mechanical aids, while others argue about the equivalence of work done regardless of the method used to lift the piano. There is no clear consensus on the correct answer, but productive dialogue is occurring around the concepts involved.

Contextual Notes

Participants are navigating assumptions about human strength and the definitions of force and work in the context of lifting heavy objects. The original question's constraints regarding the use of devices or aids are being examined but not resolved.

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Homework Statement


You cannot pick up a piano and put it on a moving truck because you (choose one)
a)cannot exert enough force to life the piano
b)cannot perform enough work to lift the piano
c)can neither exert enough force nor perform enough work to lift the piano

Homework Equations


The Attempt at a Solution


I think it's c because if you could do either a or b, you would be able to life the piano.
 
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You could perform enough work to lift the piano. Imagine connecting it to an intricate system of pulleys such that you could pull lightly on the rope for a very long distance of rope and lift the piano. It'd be the same amount of work (W=F*d). Think you could do it?
 
confuted said:
You could perform enough work to lift the piano. Imagine connecting it to an intricate system of pulleys such that you could pull lightly on the rope for a very long distance of rope and lift the piano. It'd be the same amount of work (W=F*d). Think you could do it?
I think the question is saying without any other devices, why can't you life the piano?
 
keemosabi said:
I think the question is saying without any other devices, why can't you life the piano?

Ah, but the amount of work done is the same no matter how you lift it -- that was my point.
 
1. i think the answer is a.
2. When the piano is lifted, its gravitational potential energy will increase. The piano gets this energy if you do work on it. But to do the work, you need to exert a force equal to its weight on the piano and then to move it some distance upwards.
3. Our body can't produce that kind of large force, thus it is not possible.
 
confuted said:
Ah, but the amount of work done is the same no matter how you lift it -- that was my point.
But without any other helping objects, our body can't do the work required, right?

BTW, do you think the answer is a then?
 

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