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HaoPhysics
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Member advised to use the homework template for posts in the homework sections of PF.
1. The dilemma
Work (change in energy) is defined as the exertion of a force over a distance parallel to the force.
So if force is exerted, but nothing is moved (presumably with two immovable objects), then no energy is changed.
But think about the dilemma with a person lifting 100 pounds above his head. He exerts a force of 100 pounds to counter the weight, and say he keeps it above his head for 1 hour. According to the work equation, the person has changed 0 energy in doing this act.
But he has continually exerted a force of 100 pounds for 1 hour, and now he is very tired. But according to work, he has spent 0 energy.
What am I missing?
Work (change in energy) is defined as the exertion of a force over a distance parallel to the force.
So if force is exerted, but nothing is moved (presumably with two immovable objects), then no energy is changed.
But think about the dilemma with a person lifting 100 pounds above his head. He exerts a force of 100 pounds to counter the weight, and say he keeps it above his head for 1 hour. According to the work equation, the person has changed 0 energy in doing this act.
But he has continually exerted a force of 100 pounds for 1 hour, and now he is very tired. But according to work, he has spent 0 energy.
What am I missing?