Concept of Work and Conservative Forces


by mcnealymt
Tags: concept, conservative, forces, work
mcnealymt
mcnealymt is offline
#1
Apr7-13, 07:46 PM
P: 35
Can work also be the transformation of energy? For instance, an object in free fall goes from an initial height (that has potential energy) to a final height where there is kinetic energy. If energy is conserved then how is work being done?
Phys.Org News Partner Physics news on Phys.org
The hemihelix: Scientists discover a new shape using rubber bands (w/ video)
Mapping the road to quantum gravity
Chameleon crystals could enable active camouflage (w/ video)
russ_watters
russ_watters is online now
#2
Apr7-13, 08:01 PM
Mentor
P: 22,008
Quote Quote by mcnealymt View Post
Can work also be the transformation of energy? For instance, an object in free fall goes from an initial height (that has potential energy) to a final height where there is kinetic energy.
Yes.
If energy is conserved then how is work being done?
Because all the work does is convert the energy from one form to another.
mcnealymt
mcnealymt is offline
#3
Apr7-13, 08:04 PM
P: 35
Then technically doesn't everything have work being done on it, with the exception of stationary objects.

Drakkith
Drakkith is offline
#4
Apr7-13, 08:10 PM
PF Gold
Drakkith's Avatar
P: 11,057

Concept of Work and Conservative Forces


Quote Quote by mcnealymt View Post
Then technically doesn't everything have work being done on it, with the exception of stationary objects.
No, an object moving relative to another object, but with no force being applied to it, is not having any work done on it.

That said, this is not possible in real life. All objects have constantly changing forces exerted on them.
russ_watters
russ_watters is online now
#5
Apr7-13, 09:31 PM
Mentor
P: 22,008
Quote Quote by Drakkith View Post
No, an object moving relative to another object, but with no force being applied to it, is not having any work done on it.

That said, this is not possible in real life. All objects have constantly changing forces exerted on them.
Never exactly zero, but darn close to it. An object in a close to circular orbit can stay that way for billions of years with little change in energy.
Drakkith
Drakkith is offline
#6
Apr7-13, 09:53 PM
PF Gold
Drakkith's Avatar
P: 11,057
Quote Quote by russ_watters View Post
Never exactly zero, but darn close to it. An object in a close to circular orbit can stay that way for billions of years with little change in energy.
Only in relation to the object it is orbiting around. In real life planets orbit stars, which orbit galaxies, which move in the cosmos. And then you have things like the bazillions of small objects floating through space, all of them influencing us while we do the same to them. Does that sound right?
russ_watters
russ_watters is online now
#7
Apr7-13, 10:53 PM
Mentor
P: 22,008
Quote Quote by Drakkith View Post
Only in relation to the object it is orbiting around. In real life planets orbit stars, which orbit galaxies, which move in the cosmos. And then you have things like the bazillions of small objects floating through space, all of them influencing us while we do the same to them. Does that sound right?
Sure, but the change in energy in any of those interactions is vanishingly small over vast periods of time. I wasn't trying to say you were wrong, just that in some cases, the level of precision needed to see an energy loss is really high.
Drakkith
Drakkith is offline
#8
Apr7-13, 11:45 PM
PF Gold
Drakkith's Avatar
P: 11,057
Quote Quote by russ_watters View Post
Sure, but the change in energy in any of those interactions is vanishingly small over vast periods of time. I wasn't trying to say you were wrong, just that in some cases, the level of precision needed to see an energy loss is really high.
Ah, ok. I see what you're getting at now.


Register to reply

Related Discussions
energy, non-conservative and conservative forces question Introductory Physics Homework 7
Work and conservative forces Introductory Physics Homework 1
[SOLVED] Non conservative forces: work + coefficient of static friction Introductory Physics Homework 7
Conservative and non-conservative forces-problems Introductory Physics Homework 16
Work by Gravity / Conservative Forces Introductory Physics Homework 2