Friction wastes energy
Most of the devices and machines we use every day have moving parts. When they work, some of those parts rub against each other, so frictional forces arise — and they cost something.
Those frictional forces create a resistance to the motion of such parts. When a machine is running, work has to be done against them as well, so a great deal of energy is spent on that.
Where the energy goes
The energy spent against friction is converted into heat, and the temperature of those parts rises.
Why that matters
- The energy turned into heat is energy the machine did not use for its job.
- Hot parts expand, wear away faster, and can seize or fail.
- The rubbing itself grinds the surfaces down over time.
If those frictional forces can be reduced, it becomes possible both to reduce the energy wasted and to prevent the rise in temperature. That is what the next page is about.
You can feel it
Rub your palms together hard and fast for a few seconds. They grow warm. You are doing work against friction, and the energy is arriving as heat — the same process, on a scale you can hold.