Energy _______________________________________________________________________________________________________________________________________________________________________________________________________________________ 3. Work and heat Figure 6.2. Work WORK
A system has done work if it has exerted a force on another system over some distance.
When this happens, energy is transferred from one system to another.
At least some of the energy is also transformed from one type into another during this process. One can keep track of how much energy transfers into or out of a system.
Figure 6.3. HeatTHERMAL ENERGY AND HEAT
The energy of a system or object that results in its temperature is called thermal energy.
When there is a net transfer of energy from one system to another, due to a difference in temperature, the energy transferred is called heat.
Heat transfer happens in three ways: convection, conduction, and radiation.
Like all energy transfer, heat transfer involves forces exerted over a distance at some level as systems interact.