Most people would probably agree that in everyday launguage

Most people would probably agree that in everyday launguage, \"adding heat\" and getting hotter\" are the same thing. Explain carefully what those two phrases actually mean. Then decide if they really are the same thing: is it possible for something to get hotter without adding heat to it? And is it possible to add heat to someithing without getting hotter as a result?

Solution

Adding heat and getting hotter are two different terms in physics.\"Adding heat\" is actully cause and \"getting hotter\" is an effect.

\"Adding heat\" means heat energy is given to the substance.Now this heat energy may be used by the substance in different ways.One common way is raising temperature which means \"getting hotter\".Usually when we add heat energy to number of atoms,they move faster and get hotter.Thus \"Getting hotter\" means temperature of a substance increases.

   On \"Adding heat\" (cause) ,substance is \"getting hotter\"(effect)

Adding heat however does not always increases temperature.That means it is possible to add heat to something without getting hotter as a result.For e.g when heat energy is added to a solid substance at melting point it converts solid into a liquid without increase in temperature or without getting hot.That means heat energy added to a substance is used in transformation of state without getting hot.

Similarly it is also possible for something to get hotter without adding heat to it but under certain conditions. According to thermodynamics

                                dQ =dU +dW

dQ = heat supplied,dU = internal energy,dW= work done.

Now in adiabatic process dQ = 0

That means no heat enters or leavs the system.

dU= - dW

Now according to above eq. if work is done on system,its internal energy will increase.For gases internal energy is related to temperature ,a higher internal energy means a higer temperature which inturn means \"getting hotter\".Thus in this case a substance is getting hotter without adding heat to it.