About the concept of work done (High school student)

In summary: So it would be more accurate to say that the work done by the man results in a change in the box's energy, rather than adding to the energy of the box. In summary, the conversation is discussing the concept of work done in relation to pushing a box up a slope. The formula for work done is force multiplied by perpendicular distance, which in the given example equals 750. However, there is confusion about whether this formula includes all changes in energy, such as the box gaining gravitational potential energy. Ultimately, the work done by the man results in a change in the box's energy rather than adding to it.
  • #1
FaroukYasser
62
3
Hi I am kind of Confused about an example in work done:

It says that a man applies 250 N parallel to the slope to push a box up a slope for 3 m, Now I know that the formula for work done if Force by Perpendicular distance which is 250 x 3 = 750 (which is the correct answer in my book). The thing is, isn't the object "Gaining" Gravitational potential energy ie change in its energy ie transfer of energy and therefor we should add that energy to the 750??
This is where I am confused.
Can anyone help please :)Edit: Or is the Force x Distance formula includes all changes in energy together?
 
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  • #2
FaroukYasser said:
Hi I am kind of Confused about an example in work done:

It says that a man applies 250 N parallel to the slope to push a box up a slope for 3 m, Now I know that the formula for work done if Force by Perpendicular distance which is 250 x 3 = 750 (which is the correct answer in my book). The thing is, isn't the object "Gaining" Gravitational potential energy ie change in its energy ie transfer of energy and therefor we should add that energy to the 750??
This is where I am confused.
Can anyone help please :)


Edit: Or is the Force x Distance formula includes all changes in energy together?

Welcome to the PF.

Since you are explicitly given the force needed to push the box up the ramp, that includes both the force needed to push against the friction of the box on the ramp, and the force needed to lift the box up the delta-height that it gains. Does that make more sense?
 
  • #3
berkeman said:
Welcome to the PF.

Since you are explicitly given the force needed to push the box up the ramp, that includes both the force needed to push against the friction of the box on the ramp, and the force needed to lift the box up the delta-height that it gains. Does that make more sense?

So what you mean is that if we get the component of each force and see the distance moved by each to get the total energy transferred it would add up to the Force x distance? so this formula should really be
Resultant force by displacement right?
 
  • #4
FaroukYasser said:
So what you mean is that if we get the component of each force and see the distance moved by each to get the total energy transferred it would add up to the Force x distance? so this formula should really be
Resultant force by displacement right?
It depends on what you want to compute.

If you want the work done by the man, then that is simply the force he exerts times the displacement. But to determine the final energy of the box, you'll need to consider all the forces acting, which includes gravity and friction.
 
  • #5


Hi there,

I understand your confusion about the concept of work done. Let me try to explain it to you.

Firstly, work done is a measure of the energy transferred to an object by a force acting on it. In this case, the man is applying a force of 250 N to push the box up the slope for a distance of 3 meters. The formula for work done is indeed force multiplied by the distance. So, in this case, it would be 250 x 3 = 750 J (Joules). This represents the amount of work done by the man in pushing the box up the slope.

Now, you are correct in saying that the object gains gravitational potential energy as it is moved up the slope. However, this energy is already included in the work done calculation. This is because the force applied by the man is in the same direction as the displacement of the object (up the slope). Therefore, all the work done by the man is used to increase the gravitational potential energy of the object.

In summary, the formula for work done includes all changes in energy, including the change in gravitational potential energy. I hope this helps to clear up your confusion. Keep up the curiosity and critical thinking!
 

What is work?

Work is a physical quantity that measures the amount of energy transferred when a force acts on an object and causes it to move a certain distance in the direction of the force.

What is the formula for work?

The formula for work is W = F * d, where W represents work, F represents the force applied, and d represents the distance the object moves in the direction of the force.

How is work measured?

Work is measured in joules (J), which is the unit for energy. One joule is equal to the work done when a force of one newton acts on an object and moves it one meter in the direction of the force.

What is the difference between work and power?

Work and power are related concepts, but they are not the same. Work is the amount of energy transferred when a force causes an object to move, while power is the rate at which work is done. In other words, power measures how quickly work is done.

Can work be negative?

Yes, work can be negative. This occurs when the force applied is in the opposite direction of the displacement of the object. In this case, the work done is considered to be negative, indicating that energy is being taken away from the object rather than being added to it.

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