Examples of Potential Energy
We explain that what are some examples of potential energy? The potential energy is containing a body or a substance according to its position, while at rest . It complements the kinetic energy, which depends on the movement. The potential energy is held by objects that are located at a certain height ; also the springs with spring , in which this receives a compression or an extension.
Types of potential energy
Based on the criteria mentioned, there are two types of potential energy:
- Gravitational potential energy
- Elastic potential energy
Gravitational potential energy
The gravitational potential energy is that carried by a body that is located in a position, and depends on three values, which are the mass (m), the acceleration of gravity (g) and the height of the body (h). The formula to calculate it is the following:
Ep = mgh
In calculating this energy, kilograms (kg) will be used for mass, meters over square seconds (m / s 2 ) for acceleration due to gravity, and meters (m) for height. The result, which will be in square kilogram-meters over square seconds, is equivalent to Newton-meters (Nm) or Joules (J).
Elastic potential energy
The elastic potential energy is a spring containing either to be compressed or stretched. It depends on an elastic constant (k) and the square of the distance (x) 2 that is deformed, with respect to its original length . The formula to calculate it is called Hooke’s Law , and is the following:
Ep = ½ kx 2
In the calculation of this energy, the units of the elastic constant (kg / s 2 ) and the meters (m) for the distance will be used. Applied to the formula are the square kilogram-meters over square seconds, and this is equivalent to Newton-meters (Nm) or Joules (J), which are the units of energy in the international system (SI).
Examples of potential energy
1.- What is the potential energy of a 70kg box that is located in a cellar, on a shelf that supports it at a height of 4 m?
Ep =?
m = 70 Kg
g = 9.81 m / s 2
h = 4 m
Ep = mgh
Ep = (70 Kg) * (9.81 m / s 2 ) * (4 m)
Ep = 2746.8 Kgm 2 / s 2
Ep = 2746.8 J
2.- What is the potential energy of a 20 kg jug of water that has been placed on a table at a height of 0.6 m?
Ep =?
m = 20 Kg
g = 9.81 m / s 2
h = 0.6 m
Ep = mgh
Ep = (20 Kg) * (9.81 m / s 2 ) * (0.6 m)
Ep = 117.72 Kgm 2 / s 2
Ep = 117.72 J
3.- What is the potential energy of a 0.54 kg package that is in a cupboard, 1.50 m high?
Ep =?
m = 0.54 Kg
g = 9.81 m / s 2
h = 1.50 m
Ep = mgh
Ep = (0.54 Kg) * (9.81 m / s 2 ) * (1.50 m)
Ep = 7.9461 Kgm 2 / s 2
Ep = 7.9461 J
4.- What is the potential energy of a spring that has been compressed 0.30 meters and whose elastic constant is 15 Kg / s 2 ?
Ep =?
x = 0.30 m
k = 15 kg / s 2
Ep = ½ kx 2
Ep = ½ (15 kg / s 2 ) * (0.30 m) 2
Ep = ½ (15 Kg / s 2 ) * (0.09 m 2 )
Ep = 0.675 Kgm 2 / s 2
Ep = 0.675 J
5.- What is the potential energy of a spring that has been stretched 0.45 meters and whose elastic constant is 22 Kg / s 2 ?
Ep =?
x = 0.45 m
k = 22 kg / s 2
Ep = ½ kx 2
Ep = ½ (22 kg / s 2 ) * (0.45 m) 2
Ep = ½ (22 Kg / s 2 ) * (0.2025 m 2 )
Ep = 2.2275 Kgm 2 / s 2
Ep = 2.2275 J