How do you find total potential energy?

Question

to get total potential energy, do u just add up all the PE's and wut about gravitational potential energy what do you do with that?

Answer 1

you factor in 9.8 meters per seconds^2 and the mass in kilogrmas and multiply them then you get the force which would be the total potneial energy an object could ammount to.

Answer 2

Gravitational Potential Energy
The two examples above illustrate the two forms of potential energy to be discussed in this course - gravitational potential energy and elastic potential energy. Gravitational potential energy is the energy stored in an object as the result of its vertical position (i.e., height). The energy is stored as the result of the gravitational attraction of the Earth for the object. The gravitational potential energy of the massive ball of a demolition machines is dependent on two variables - the mass of the ball and the height to which it is raised. There is a direct relation between gravitational potential energy and the mass of an object; more massive objects have greater gravitational potential energy. There is also a direct relation between gravitational potential energy and the height of an object; the higher that an object is elevated, the greater the gravitational potential energy. These relationships are expressed by the following equation:

PEgrav = mass * g * height
PEgrav = m * g * h
In the above equation, m represents the mass of the object, h represents the height of the object and g represents the acceleration of gravity (approximately 10 m/s/s on Earth).

To determine the gravitational potential energy of an object, a zero height position must first be arbitrarily assigned. Typically, the ground is considered to be a position of zero height. But this is merely an arbitrarily assigned position which most people agree upon. Since many of our labs are done on tabletops, it is often customary to assign the tabletop to be the zero height position; again this is merely arbitrary. If the tabletop is the zero position, then the potential energy of an object is based upon its height relative to the tabletop. For example, a pendulum bob swinging to and from above the table top has a potential energy which can be measured based on its height above the tabletop. By measuring the mass of the bob and the height of the bob above the tabletop, the potential energy of the bob can be determined.

Since the gravitational potential energy of an object is directly proportional to its height above the zero position, a doubling of the height will result in a doubling of the gravitational potential energy. A tripling of the height will result in a tripling of the gravitational potential energy.

Answer 3

The formula we use for determining P.E is m g h.

The height ‘h’ is measured from a point ‘A’ which we have chosen to be zero.

If a point B is vertically up above the reference line, then the height is taken to be positive and if it is below, the height is taken to be negative.

Naturally the potential energy at A is zero.
The potential energy at B is mgh, if ‘h’ is positive, i.e., if it is up.
The potential energy at B is - mgh, if ‘h’ is negative, i.e., if it is down.

However the difference is P.E between the two points is mgh, since P.E at A is zero.


Suppose, we are in the top floor of a tall building the height of which is H meter from the ground.

Then the P.E of stone on the ground is -mgH.

The P.E of a point at the center of earth is therefore - mg (H + R.)

Yet, the difference in P. E between the point on the top of the building and the center of earth is mg (H+R).

However the formula ‘mgh’ for finding P.E is only an approximate one and is valid only if the difference in distance between two points ‘h’ is small.

The correct formula for P.E is - G M m/R, and the zero P.E is taken to be at infinite distance from the center of earth. G is the universal gravitational constant, M is the mass of earth, m is the mass of the object and R is the distance of the object from the center of earth.

On the surface of earth (ground) the potential energy is - GMm/R where R is the radius of earth.

On the top floor of the building of height H from the ground,
the P.E is - G Mm/ (R+H).

Since H is small compared to the value of R, it can be shown that the difference in
potential energies between the two points (ground and top of the building) to be mgH.

Thus understand that the P.E at a point is the same as the gravitational P.E at a point. And what we calculate is the difference in P.E between two points when we use the formula mgh.