How do things become hot or cold?
In: Physics
It’s a matter of energy.
Energy cannot be created or destroyed, you can just transform it.
So let’s say you have a piece of metal and start hammering it. After a while you will notice that the metal is hotter even if it was at room temperature, the same for the hammer. This happens because you put kinetic energy in your blow and the metal cannot absorb it all, so the excess transform in heat.
The temperature of something is due to the motion speed, rotational speed and vibrational frequency and intensity of its molecules. If some phenomenon causes some of these parameters to increase the affected object will get hotter. Vice versa, if they decrease it will get colder.
Particle theory dictate that there is no such thing as heat, that heat is just a human perception.
The particles in hot objects have more kinetic energy, therefore they move around faster. The opposite is true for cooling things down.
Let’s say for example, we cram a large quantity of people into a box, and we push one of them. That person will hit other people, who in turn will hit other people, et cetera, et cetera, granting them kinetic energy and turning them into a grumbly mess. If we replace the people with atoms, and do the same thing, you have just applied heat.
By cooling them down, we hold one of them still while everyone’s still hitting each other from the previous experiment. They’ll collide with the person we’re holding, and he won’t hit anyone because we’re holding him still. By removing energy from the mass of people we have stopped them moving as much. If the people were atoms, we have removed heat.
TL;DR heat is just kinetic energy of individual particles.
if this were tagged as “physics” I’d say by either adding or removing energy as “heat” is just a statistical description of the movement of atoms/molekules in a “thing”.
so adding energy either by adding electrical energy, kinetic energy (dropping it from somewhere, accelerating it somehow), creating friction (rubbing it against something), absorbing energy from the sun, etc will heat something up. to cool something down you need to do the reverse, which is generally harder.
since it’s tagged as chemistry….do you mean when you combine them? when you combine two reagents and there’s a reaction that causes the result to get hot then it’s because the ions in your reagents reacted in a way that created a surplus of energy.
Latest Answers