Work involves a force (a push or pull) acting upon a moving object, either with its motion or against its motion. Work is a means of tranforming energy from one form to another. A gain (or loss) in a mechanical energy form (kinetic or potential) is accompanied a loss (or gain) in some other form of energy - mechanical or non-mechanical. In all instances, work is simply a way of transferring energy across the system boundary (into or out of the object) or a way of changing potential energy into kinetic energy (or vice versa). 
 

This question requires you to think hard about energy.  A situation involving work is described and you must identify the way in which energy changes form. You must complete the statement: energy is changed from ______ form into ______ form. The first blank refers to the energy that was present before the work was done and was lost as a result of the work. The second blank refers to the new form of energy that resulted because of the work that was not present before the work was done. To determine these two forms of energy, you must know your energy forms and then be able to apply that knowledge to this situation. Here is a short description of the most common forms.

Kinetic Energy (KE):   Kinetic energy is the energy of motion. The amount depends (in part) on speed. Fast-moving objects have more KE than slow-moving objects. Ask yourself if there is any change in speed for this situation. If there is, then KE will be involved in the energy transformation.

Potential Energy (PE): Potential energy (a.k.a. gravitational potential energy) is the stored energy of vertical position. The amount depends (in part) on height. Objects at higher positions have more PE than those at lower positions. Ask yourself if there is any change in height for this situation. If there is, then PE will be involved in the energy transformation.

Chemical Energy (CE):  Chemical energy is the energy stored in chemicals. Fuels like gasoline in a car and carbodydrates in the human body are sources of chemical energy.  When a car burns gasoline, it is tranforming CE into another form. And when a human expends effort to push on an object, it is burning carbohydrates and transforming CE into another form. Chemical energy is often transformed into mechanical forms such as kinetic energy (motion) or potential energy (height). Ask yourself if a fuel or a person is involved in the work that is done on the object. If there is, then CE is probably being tranformed into another form of energy.

Dissipated Energy (DE): Dissipated energy is the energy that results when resistance forces act upon objects. Resistance forces such as friction and air resistance and even forces from the surroundings applied against an object's motion cause mechanical energy to be dissipated or changed into other non-mechanical forms. These non-mechanical forms are forms like thermal energy (heat) and sound energy.  For instance, friction is the resistance force on a skidding object that serves to change the kinetic energy into non-mechanical forms like thermal energy (heat).  We call this resulting form of energy dissipated energy​.