# What's the work done moving an object up and then back down?

• Majestic247
In summary, when lifting a weight a distance x and then lowering it back down, the displacement is 0 but the distance traveled is 2x. The work done in this scenario will be 0, according to the precise definition used by physicists. This is because the work is positive when the force and displacement are in the same direction, and negative when they are in opposite directions. In this case, the forces and displacements cancel each other out, resulting in a net work of 0.
Majestic247
If i lift it a distance x then bring it back down, so that the displacement is 0 but distance traveled is 2x.

Will work done be doubled or will it be 0?

0

Chestermiller said:
0

Why is this so?

Majestic247 said:
Why is this so?
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

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

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.

What is the definition of work?

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.
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.

Chet

## 1. How is work defined when moving an object up and then back down?

Work is defined as the force applied to an object multiplied by the distance it is moved in the direction of the force. In this case, the force is against gravity when moving the object up and with gravity when moving it back down.

## 2. Is the work done moving an object up and then back down always the same?

No, the work done will vary depending on the weight of the object and the distance it is moved. The greater the weight and distance, the more work is required.

## 3. What is the role of potential energy in the work done moving an object up and then back down?

When an object is moved up, it gains potential energy due to its increased height. This potential energy is then converted back into kinetic energy as the object moves back down, allowing it to do work.

## 4. Does the speed of the object affect the work done moving it up and then back down?

Yes, the speed of the object can affect the work done. The faster an object is moved, the more work is required to overcome air resistance and friction. However, if the object is dropped from a height, it will gain more kinetic energy and therefore do more work when it hits the ground.

## 5. How can the work done moving an object up and then back down be calculated?

The work done can be calculated by multiplying the force applied (in the direction of motion) by the distance the object is moved. This can be represented as W = Fd. The unit for work is joules (J).

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