When people hear the term work, they might think of someone lifting a heavy object over their head or working a long shift at a restaurant. However, when scientists talk about work, it is more complicated than just exerting a force and moving an object. The scientific definition of work is based on the fact that energy is transferred when an object moves. The direction of the object’s movement and the relative directions of the force and displacement determine whether the work done is positive, negative or zero.
A simple example of work is throwing a ball. If the ball is thrown straight up, it goes a far distance. The distance traveled is determined by the force of the thrower and the speed of the ball. This is known as the work-energy principle.
The work that is done is equal to the force times the distance traveled. However, the work can also be calculated using an additional variable called the angle theta between the force and the displacement. This is expressed as
If the forces are constant, work is equal to the change in kinetic energy of the body, or
An example of an in-conservative work is the downward force of gravity on a ball. This is an example of in-conservative work because the ball loses kinetic energy as it descends, even though the net force exerted by gravity is not changing. The work done by an in-conservative force is also a function of the difference between its potential energy and kinetic energy, or
