Can energy be used?

The law of conservation of energy is an iron foundation

• The law of conservation of energy is considered to be the iron foundation of physics. So far, no process is known in which energy is lost in any form.
• A consequence of the law of conservation of energy is that, although energy can be converted from one form to another, this is complete, that is, there is no loss.
• For example, in free fall, in which a body is released from a certain height, the positional energy (also called potential energy) is converted into kinetic energy of the body. Small parts of the kinetic energy are also converted into frictional energy (air).

But when can energy be "used"?

• In everyday life it is often said that the energy is consumed or consumed. the energy consumption must be reduced. But is that even possible when the principle of conservation of energy applies?
instagram viewer
• In fact mix here Technical terms and slang meanings. In physics, a system has energy when it can do some kind of work. A hot gas can drive a piston (steam engine), a flywheel can drive a bus or electricity can set a machine in motion.


Difference between energy and work

In everyday life, the terms energy and work have different meanings. Against it …

• However, in this context one always speaks of "used" energy, which is of course not correct from the point of view of physics, because the existing heat energy, The rotational energy or the electrical energy is not consumed in the work, but converted into another, desired form of energy (usually Kinetic energy).
• But can that even be true? Because if you bump a pendulum or push a little cart (giving it kinetic energy), then both will come to rest at some point. Wasn't energy simply "consumed" here?
• To the observer, of course, it seems that way. But here the energy bill was made without the inevitable friction: the pendulum fights against air friction, the little cart against the rolling friction of its wheels. A small part of the kinetic energy is always converted into thermal energy. If this experiment were to be carried out in a closed, heat-insulating box, a slight increase in temperature could be measured with a very precise thermometer.
• So if you have the feeling that energy is being lost, then this is usually converted into (not quite as valuable) thermal energy, which is then distributed in a large room (by diffusion). The temperature rise is then imperceptible.

Conclusion: Even if energy consumption is talked about in everyday life, it is physics always the conversion of energy meant in other forms of energy.