ABSTRACT
Kinetic energy is the energy of motion. An object which has motion, whether it be vertical or horizontal motion has kinetic energy. There are many forms of kinetic energy, which include vibrational, rotational, and translational (energy due to motion from one location to another). The basic equation to determine kinetic energy is written as
K.E. = mv
Or written another way:
K.E. = ×12 mv
where: K.E. = kinetic energy (Newtons) m = mass of the object v = speed of the object (velocity)
Example
Potential energy is the same as stored energy. Potential energy exists whenever an object that has mass has a position within a force eld. The most everyday example of this is the position of objects in the earth’s gravitational eld. Another good example of potential energy is a round object balanced atop a pyramid. The round object is not in motion, but has the potential to be in motion. The equation to determine potential energy is listed as
P.E. g= m h
where: P.E. = potential energy (in Joules) m = mass of the object (in kilograms)
g = gravitational acceleration of the earth (9.8 m/s2) h = height above earth’s surface (in meters)
Example
Another type of potential energy important to safety professional is elastic potential energy. Elastic potential energy is the energy stored in elastic materials as the result of their stretching or compressing. Elastic potential energy can be stored in rubber bands, bungee cords, trampolines, springs, an arrow drawn into a bow, ad so on. The amount of elastic potential energy stored in such a device is related to the amount of stretch of the device. The more stretch of the material, the more energy that is stored. It is important to introduce the reader to Hooke’s Law, which states that if a spring is not stretched or compressed, then there is no elastic potential energy stored in it. The spring is said to be at its equilibrium position. The equilibrium position is the position that the spring naturally assumes when there is no force applied to it. In terms of potential energy, the equilibrium position could be called the zeropotential energy position. There is a special equation for springs that relates the amount of elastic potential energy to the amount of stretch (or compression) and the spring constant. According to Hooke’s law, the force required to stretch the spring will be directly proportional to the amount of stretch. This equation is written as follows:
P.E.elastic =
kx2 2
where: P.E. = potential energy (elastic) (Joules) k = spring constant (N/m2) x = amount of compression (distance in meters)
Example
Force is a push or pull upon an object resulting from the object’s interaction with another object. Whenever there is an interaction between two objects, there is a force upon each of the objects. Force is a quantity that is measured using the SI unit known as the Newton. A Newton is abbreviated as “N.” To say “10 N” means 10.0 N of force. One Newton is the amount of force required to give a 1-kg mass an acceleration of 1 m/s2.
