The change in GPE equals the negative of the work done by gravity.UMath1 said:Gravitational potential energy is equal to negative work.
Work done by who? To lift the object the lifter must do work on it.UMath1 said:But in the case of lifting an object upwards, the work done on the object would be 0.
True, the net work is zero, but that only means that there is no change in kinetic energy.UMath1 said:The work on the object by the lifter would equal the work on the object by gravity. Then, how does the object get GPE?
Not if there's an external force (the lifter) doing work on the object.UMath1 said:Isn't it true however that -Delta K=Delta U? Where U is potential energy, and K is kinetic energy.
Yes, that's the work energy theorem.UMath1 said:It is also true that Wnet= Delta K.
Nope.UMath1 said:So if net work is zero, then change in kinetic energy should be zero, and therefore change in gravitationak potential should be zero as well...?
Realize that GPE already accounts for the work done by gravity. So if you use GPE you do not also treat gravity as doing work--to do so would be to count it twice.UMath1 said:Why does the lifter count as external but gravity does not?
You can think of it that way. The conservative force of gravity is already included in the GPE; the lifter's non-conservative force is not.UMath1 said:Is it because the lifter applies a nonconservative force?
It is possible that the lifter will be a conservative force, like a spring. Then the lifter will have its own potential energy which will be different from GPE, like elastic potential energy.UMath1 said:Is it because the lifter applies a nonconservative force?
Potential energy is the energy that an object possesses due to its position or state. It is stored energy that can be converted into other forms of energy, such as kinetic energy.
An object gains potential energy when it is lifted or raised to a higher position against the force of gravity. This requires work to be done on the object, which results in an increase in its potential energy.
An object's potential energy is affected by its mass, height, and the strength of the gravitational field it is in. The higher an object is lifted and the more massive it is, the greater its potential energy will be.
Yes, an object can have potential energy without being lifted if it is in a state of potential energy, such as a compressed spring or a stretched rubber band. The potential energy in these cases is due to the object's position or state, rather than its height.
Potential energy and kinetic energy are two forms of energy that can be converted into each other. When an object gains potential energy, it can then release that energy and convert it into kinetic energy as it falls or moves. The total energy of the object, known as mechanical energy, remains constant throughout this conversion process.