The discussion centers on the concept of work done when lifting and lowering an object. When an object is lifted a distance x and then returned to its original position, the total displacement is zero, resulting in zero net work done according to the physicist's definition of work. Positive work occurs when the force and displacement are in the same direction, while negative work occurs when they are in opposite directions. Thus, despite the distance traveled being 2x, the net work remains zero due to the opposing forces during the lifting and lowering processes.
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Chestermiller said:0
What are your thoughts on this? How much work do you do on the weight while raising it? How much work do you do on the weight while allowing it to be lowered? What are the directions of the forces you apply while raising and lowering, and what are the corresponding directions of the displacements? How do the directions of the forces compare with the directions of the displacements?Majestic247 said:Why is this so?
Chestermiller said:What are your thoughts on this? How much work do you do on the weight while raising it? How much work do you do on the weight while allowing it to be lowered? What are the directions of the forces you apply while raising and lowering, and what are the corresponding directions of the displacements? How do the directions of the forces compare with the directions of the displacements?
Chet
There are several different dictionary definitions of the word "work," and only one of these is the mathematically precise definition that physicists use to calculate the quantity they call "work." In physics, the work is positive if the force and the displacement are in the same direction, and negative if the force and displacement are in opposite directions. So, if you exert a force upward to move a weight upward, the work you do is positive. If you are exerting a force upward and the weight is moving downward, the work you do is negative (the weight is actually doing work on you). In both cases, according to a layman, you have done a net amount of work, but, according to the physicist's definition, the net amount of work you have done is zero.Majestic247 said:I do the same work on raising and lowering the weight. My thought was that since a work is done to raise it up a distance x and then bring it down a distance x it should be doubled, however my father said that the displacement is overall 0 so the work it did was zero but I still can't understand why this is so.