Environmental Engineering Reference
In-Depth Information
to equalize the energy levels. For example, a rapidly flowing stream (high kinetic energy)
that comes into contact with a static boulder (no kinetic energy) tends to push the boulder
into motion. In doing so, the stream loses energy by friction but imparts some of this
energy to the boulder in the form of motion (kinetic energy). Similar principles apply to
chemical energy.
One way of looking at these transfers of energy is to regard them as movements down
an energy gradient. It is easier to see this principle in the example of heat energy, for we
can all appreciate that heat moves from hotter to cooler areas. Heat the end of a metal bar
in a fire and the heat will move along the metal until it burns your fingers! Heat energy in
this case moves down the energy gradient in the bar. The same general processes operate
with other forms of energy (Figure 2.5)
Figure 2.5
Examples of energy gradients.
