Energy and work occupy an important part of our ordinary life and are among the most important topics in physics. Work in terms of physics has quite a different meaning than the work we normally think of. In physics, work is done only when an object is moved in the direction of the applied force.
Energy in physics is defined as the ability to do work. That
makes sense, right? After all, the more energy you have, the
more schoolwork you can do...right. So anyway, another way to
see it is that work is the force exerted multiplied by the
distance, or W=FD. That also makes sense. If you push a really
heavy object a certain distance, you do more work than if you
push a lighter object that same distance.
The energy stored in the various sources covered in this page is,
in one way or another, derived from the energy of the sun. For
instance, when we burn wood, we are simply converting the sun's
power that was stored in the growing plant into radiant (light)
and thermal (heat) energy. Hydroelectric power is derived from
the running water that flows from higher elevations to lower
elevations. Again, it is the sun that provided the energy to
evaporate water from lower heights and transported it to the
upper heights as rain. So all the energy we deal with comes from
the sun.
You've already read about kinetic and potential energy. Other
types of energy that are discussed in this site are derivatives
of kinetic energy. For instance, thermal energy is kinetic
energy in the form of heat.
Read on to discover a much more in-depth view of the physics of
energy.
