If a mass became pulled up from Earth, its U increases and its K

In summary, the conversation discusses the concept of potential energy and how it relates to gravity. It is noted that the potential energy of a mass increases as it is pulled up from Earth and decreases as it is pulled into space. The reference point for potential energy is taken to be 0 at infinity. The idea that gravity is not conservative in large scale is questioned, as potential energy can still be negative even in space.
  • #1
Ignition
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If a mass became pulled up from Earth, its U increases and its K decreases, but if it became pulled into space, its U becames 0. So, could we say that Gravity is not a conservative field in large scale, but a negative Energy?
 
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  • #2
Ignition said:
If a mass became pulled up from Earth, its U increases and its K decreases, but if it became pulled into space, its U becames 0.
Realize, since we take U = 0 at infinity as the reference point, that the U of the system starts out negative and increases to zero.
So, could we say that Gravity is not a conservative field in large scale, but a negative Energy?
Not sure why you'd conclude that gravity is not conservative at large scale. Realize that the sign of potential energy depends on your reference point.
 
  • #3
Ignition said:
If a mass became pulled up from Earth, its U increases and its K decreases
Well, no. If it is pulled into space, then there is a force acting on it which would increase its total energy. It might well keep the same K (Kinetic energy) while increasing its potential energy. If it already has a large kinetic energy on Earth and uses only that energy to move away from the earth, with no external force, then the kinetic energy decreases while the potential energy increases so the total energy remains the same.

, but if it became pulled into space, its U becames 0.So, could we say that Gravity is not a conservative field in large scale, but a negative Energy?
Again, no. Its potential energy does NOT become 0 "in space". For gravitational problems, potential energy (which, as Doc Al said, is always relative to some reference point) is taken to be 0 at infinity, not just in space. If you take an object to have a very large negative potential energy on Earth (and considering only the Earth's gravity) the at several light years from the Earth it would have a very small, but still non-zero negative, potential energy.
 
  • #4
Ok, great, you are very good.
 

1. How does increasing mass affect the potential and kinetic energy of an object?

As the mass of an object increases, its potential energy also increases. This is because potential energy is directly proportional to mass and height. The potential energy of an object at a particular height is given by the formula PE = mgh, where m is the mass, g is the acceleration due to gravity, and h is the height. On the other hand, the kinetic energy of an object remains unchanged as mass is not a factor in its calculation, which is given by KE = 1/2mv^2, where m is the mass and v is the velocity of the object.

2. How does lifting an object affect its potential and kinetic energy?

Lifting an object increases its potential energy and decreases its kinetic energy. This is because lifting an object requires work to be done against gravity, which is stored as potential energy. At the same time, the object's velocity decreases as it is being lifted, resulting in a decrease in kinetic energy.

3. What happens to an object's energy when it is pulled up from Earth's surface?

When an object is pulled up from Earth's surface, its potential energy increases while its kinetic energy decreases. This is because work is being done against gravity, increasing the object's potential energy, while its velocity decreases due to the opposing force of gravity, resulting in a decrease in kinetic energy.

4. How do changes in mass and height affect an object's potential energy?

An object's potential energy is directly proportional to both its mass and height. This means that increasing either the mass or height of an object will result in an increase in potential energy. Conversely, decreasing the mass or height of an object will result in a decrease in potential energy.

5. Is there a limit to how much potential energy an object can have?

In theory, there is no limit to the potential energy an object can have. As long as the object has mass and is at a height above Earth's surface, it will have potential energy. However, in practical situations, there are limits to how much potential energy an object can have, as it cannot be lifted infinitely high and the object's mass is limited. Additionally, factors such as air resistance and other external forces can also affect the potential energy of an object.

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