heat and temperature

[devayaani]

Thank you for explaining.
I know the temperature rises as the heat input is increased. I know the kinetic energy of the moving atoms in a substance.
Actually what is the relationship between temperature and heat?
What is temperature?
Can you explain the concept behind this without resorting to very much of mathematics?
Thanks.

[vascop]

Right. Heat is energy. Let's think about a piece of iron of a given mass. If you add a certain amount of heat to it it's temperature will rise to a certain value. Assuming that no heat is lost, if you add the same amount of heat again then the temperature will go up by the same amount as before - so it will double.

A good way to think about it is to think of a water tank. If you pour water into it then the water gets deeper. If you double the amount of water in the tank, then the water will be twice as deep. So the depth of water is like the temperature and the amount of water is like the amount of heat.

If you make the tank thinner left to right, but keep the front to back dimension the same then that's like having a piece of iron which has less mass and so the same amount of heat will produce a higher temperature and correspondingly the water will be higher in the thinner tank.

[eltelioni]

You are almost there.

Temperature is a measure of the average kinetic energy of the atoms in a substance. In gasses and liquids the kinetic energy is in movement of the molecules and also in vibrations of the molecules. In solids it is just in the vibrations. When you bring together two objects at different temperatures, heat energy will flow from the hotter one to the cooler until both objects are at the same temperature. To see how this works consider what happens when a hot block of iron is dropped into a bowl of cooler water. At the surface of the iron block, the rapidly jiggling iron atoms hit water molecules and transfer energy to them. This cools the iron and warms the water. Eventually equilibrium is reached, where the energy transfer from the iron to the water is the same as the energy transfer from the water to the iron. They are then at the same temperature.

[eltelioni]

Different materials require different amounts of energy to increase the temperature by the same amount. For example, to increase the temperature of 1 gram of water by 1 degree C you need to add 4.2 Joules of energy, but to increase the temperature of 1 gram of iron by 1 degree C you only need to add 0.45 Joules. This seems counter intuitive because iron is denser than water. The reason is that molecules share the kinetic energy amongst all their degrees of freedom. In the iron block, the energy just goes to vibrating the atoms in the crystal lattice. In the water it is shared between vibrations of the molecules and movement of the water molecules, so more energy is required to raise its temperature.

I hope this makes sense.

[devayaani]

Thank you both for the good information and further clarification

[himupnorth]

In very simple terms.
Everything is made of particles, heat energy moves these particles, temperature is a measure of how fast the particles are moving.
This means that a bath of water and a cup of water can be at the same temperature as their particles can move at the same speed but they will not have the same amount of heat energy, that is unless you've a very large cup and a tiny bath.