Temperature

So what is cold and hot?

What makes something cold or hot? Physically, what is it?

 

Atomic movement. small amount = cold....fast/large amount = hot

 

Like tecoyah said it's the kinetic energy in the random motions of atoms/molecules. More kinetic energy means more motion which means more heat. These movements then quickly induce dipole oscillations which cause rapidly changing electromagnetic fields which then lead to the emission of photons or thermal radiation. The kinetic energy in these random motions (or heat) can be transferred in 3 ways. First, convection can move the material containing heat in bulk to a different place. Second, conduction is the act of imparting kinetic energy through conservation of momentum from one atom/molecule to another. Third, radiation converts the kinetic energy of motion to energy carrier particles (photons) via quantum electrodynamic processes. The carrier particles (photons) then transmit the energy over vast distances at the speed of light where they are then converted back to kinetic energy of motion when the interact with atoms/molecules.

Moving heat from one area of your home to another via the air handler (fan) is convection. Material (air) is moved in bulk.

Touching a hot stove is conduction. The atoms/molecules of the heating element make physical contact with atoms/molecules of your hand.

Earth warming via the Sun is radiation. Photons can travel through a vacuum and then will interact with atoms/molecules in the atomsphere, land, and ocean causing them to move faster (get hotter).

 

It is all relative!


What makes something cold or hot?
Compared to what?

What makes something cold or hot?
Because I say so.

Anything above Absolute Zero is hot.



Moi

 

to be a accurate there is no such thing as cold, cold is the absence of heat, cold is a subjective from a human perspective...

Fahrenheit and Celsius temp scales record temps from a human perspective

when temperature is scientifically measured on the Kelvin scale from absolute zero, measures degrees of heat, not cold...

 

Isn't heat the absence of cold?

 

No, or at least not from a scientific standpoint. Heat is a measurement of movement of atoms. All atomic movement ceases at absolute zero (exactly 0 Kelvin or approximately -273.1 Celsius) so this is an absolute lower limit of temperature.

 

Yes, and that would be cold.

So if you take away cold, no movement of molecules, you have heat.

 

You cannot take away no movement....

You can make particles move (add heat) but you cannot take away cold.

 

Sure you can.

Put your hands next to a fire when you are chilly, you can most certainly take away cold.

 

From a scientific perspective, you are adding heat.