What is energy's role in natural forces like gravity and magnetism?

[grantwilliams]

If force was applied to an object will there be work done?

Isn't that only true if force is in the same direction as motion?

 

[Drakkith]

Isn't that only true if force is in the same direction as motion?

No, if you apply a force against an object to slow it down you have done work.

 

[grantwilliams]

No, if you apply a force against an object to slow it down you have done work.

And I guess a torque applied causes work to be done if the object has a radial displacement.. my bad.

 

[Momento]

No, if you apply a force against an object to slow it down you have done work.

Makes sense. A force was applied over a distance to stop a moving object which represents this model: W = F x D?

Thats way work is done?

 

[Momento]

Is it safe to say that "Energy" is the measurement of work done in a system? And that Force is crucial for Work to be converted?

 

[Drakkith]

Is it safe to say that "Energy" is the measurement of work done in a system?

I believe that is pretty much the definition of energy, the ability to do work.

And that Force is crucial for Work to be converted?

I'd say that force is the reason work happens. If a particle didn't feel a force from another particle, nothing would ever change and no work could be done.

 

[Momento]

I believe that is pretty much the definition of energy, the ability to do work.

A very nice explanation! Makes sense it can't be created or destroyed you can't create a measuring unit right ?

I'd say that force is the reason work happens. If a particle didn't feel a force from another particle, nothing would ever change and no work could be done.

I totally agree! Thinking of all kinda of energy I can't find force out of the picture and besides! W = F x D!

 

[Momento]

I believe that is pretty much the definition of energy, the ability to do work.

If I had a debate and the topic of energy came up, its possibile to say that energy is the measurement of work done? It makes more sense that way to a person that keeps asking where did it originate from.

 

[haruspex]

If I had a debate and the topic of energy came up, its possible to say that energy is the measurement of work done? It makes more sense that way to a person that keeps asking where did it originate from.

Not really. That only deals in terms of changes in energy. In view of the equivalence of mass and energy, and the affect these have on gravity (according to GR), there must be a sense of absolute total of energy of a system.
Wrt Drakkith's definition of energy as the ability to do work, I don't see how that deals with heat energy, particularly in a system at uniform temperature.

 

[Drakkith]

If I had a debate and the topic of energy came up, its possibile to say that energy is the measurement of work done? It makes more sense that way to a person that keeps asking where did it originate from.

Using the basic definitions of what energy is, I would say yes. Just remember that energy is potential work. An asteroid flying through space has a lot of kinetic energy, but that doesn't mean that it will hit something and perform work.

Not really. That only deals in terms of changes in energy. In view of the equivalence of mass and energy, and the affect these have on gravity (according to GR), there must be a sense of absolute total of energy of a system.
Wrt Drakkith's definition of energy as the ability to do work, I don't see how that deals with heat energy, particularly in a system at uniform temperature.

Have you considered potential energy? Matter has with it the potential to cause work if it annihilates with antimatter, thus it has potential energy. Not only that, but the bonding of matter in different ways, such as an electron falling down an energy level and emitting a photon, also has the ability to do work. Since energy is conserved the atom that the electron occupies is now less massive than before.

I see it as everything has potential energy. A ball on top of a hill doesn't necessarily roll down the hill. It could be stuck on a rock or something. It still has the potential to be dislodged and roll down, which means that it still has potential energy whether or not it will roll down now, two weeks from now, or never.

 

[Momento]

Thank you everyone for this very very interesting topic! So far I've understood energy much more clearly than I have before so as the main role of force and without it work can't really be done! I looked upon so many rules in physics that really do relate in many ways!

I really appreciate all you're effort for this!

Best Regards,
Momento