- #1
hms.tech
- 247
- 0
I believe that I have found a serious mistake in the wiki entry about Potential Energy.
notice the -ve sign in the formula on the web page.
According to the article, the definition of this term is : the gravitational potential at a location is equal to the work (energy transferred) per unit mass that is done by the force of gravity to move an object from infinity to the location.
The wording itself is mathematically inconsistent with the formula -[itex]\frac{GMm}{r}[/itex].
Here is the problem :
It is clear that gravity does positive work on the object when it is moved from [itex]\infty[/itex] to some distance "x" . (this is simply because Work = F.s ; Force and displacement are in the same direction).
Why is it that the Formula contains a -ve sign when gravity is doing positive work on the object ; hence transferring energy to the object (by the intuition of "work").
The energy of the object is increasing .
Say we take a point X= 2 m
By definition , Gravitational potential energy is the work done(by gravity) to move the object from infinity to X=2 m .We plug in the values and we get an answer which is -ve .
This -ve answer implies that the work done by gravity in moving the mass from infinity to X=2m is NEGATIVE but we have already established that gravity does +ve work on any object which moves closer to itself ( such as this object moving closer to the Earth) [since work = F.s, and force and displacement are in the same direction]
This is clearly a contradiction !
Please help, I am ecstatic about this conundrum.
notice the -ve sign in the formula on the web page.
According to the article, the definition of this term is : the gravitational potential at a location is equal to the work (energy transferred) per unit mass that is done by the force of gravity to move an object from infinity to the location.
The wording itself is mathematically inconsistent with the formula -[itex]\frac{GMm}{r}[/itex].
Here is the problem :
It is clear that gravity does positive work on the object when it is moved from [itex]\infty[/itex] to some distance "x" . (this is simply because Work = F.s ; Force and displacement are in the same direction).
Why is it that the Formula contains a -ve sign when gravity is doing positive work on the object ; hence transferring energy to the object (by the intuition of "work").
The energy of the object is increasing .
Say we take a point X= 2 m
By definition , Gravitational potential energy is the work done(by gravity) to move the object from infinity to X=2 m .We plug in the values and we get an answer which is -ve .
This -ve answer implies that the work done by gravity in moving the mass from infinity to X=2m is NEGATIVE but we have already established that gravity does +ve work on any object which moves closer to itself ( such as this object moving closer to the Earth) [since work = F.s, and force and displacement are in the same direction]
This is clearly a contradiction !
Please help, I am ecstatic about this conundrum.