FEBRUARY 5, 2014

• If you are working on your test from yesterday, you will have 10 more minutes of class time. If you do not finish you will have to come in before or after school to finish it.

• If you have completed your test, or finish before 10 minutes, you are to work on the bell ringer that will be on the screen. YOU WILL REMAIN SILENT WHILE OTHERS ARE WORKING ON THEIR TEST!

February 5, 2014

What is the density of an irregular shaped rock with a mass of 14 grams, and when placed in a graduated cylinder of mL of 10 water, displaces it to 17 mL?

This is not the picture of the Problem described above!

HEAT

• What happens to an ice cube when you hold it in your hand?

• We have all experienced the effects of heat but what is heat?

HEAT

• Heat is a form of energy (not matter) caused by the motion of atoms (matter).

• Heat is the sum of the kinetic energy of each atom in a sample.

• This means that a bucket of hot water has more heat (energy) than a teacup of hot water.

• BTW: What is cold?

Remember Heat is NOT Temperature

• Temperature is related to heat but isn’t the same thing. Temperature is a measure of the average speed of the atoms in something.

• The average speed of atoms in a hot object is fast; the average speed of the atoms in a cold object is slower.

Diffusion

• Diffusion is the tendency of molecules to intermingle due to their kinetic energy.

• The tendency of molecules to spread out from an area of high concentration to an area of low concentration is diffusion.

Try This

• If you want to warm up a swimming pool which would be a better way?– Warm the water by adding a teacup of water at

100 degrees C– Warm the water by adding a bucket of water at 50

degrees C

– The bucket of water is less hot but has more molecules so it has more heat energy.

How’s About This?

• If you mix a cup of water at 20 degrees C with a cup of water 80 degrees C, what do you think the temperature of the water will be?

• The hot and cold molecules collide and exchange energy. The final temperature will be halfway between the two temperatures.

So…. Back to Heat

• CONVECTION is the transfer of heat through the motion of gases and water.

• Warm air rises and Cold air sinks (Density)• As this occurs you get a circulation of heat.

Now Let’s Experiment

Convection in Earth’s Atmosphere

Did you Know?

Hawks use convection to soar. They are lifted higher in the sky by the rising currents of warm air.