Please complete section 13.2 assessment• Page 451

• You have approximately 10-15 minutes, depending. If you don’t finish, please do it for homework.• I will check it tomorrow.• If you finish, please work on something else.

14.1 Temperature, Thermal Energy, and Heat

• Key Concepts: What are the three common temperature scales?• How is thermal energy related to

temperature and heat?• What does having a high specific heat mean?

• Key terms: temperature, Fahrenheit scale, Celsius scale, Kelvin scale, absolute zero, heat, specific heat

Temperature• Temperature is a measure of the AVERAGE

kinetic energy of the individual particles in matter. (note: how is this different from thermal energy?)

• Lower-temperature particles aren’t moving as much, so they have a lower kinetic energy than high-temperature particles.

• To record temps, we use thermometers.

How does a thermometer work?• When the tube is heated, the particles speed up and spread out,

increasing the volume, and the liquid moves up the tube. • The red colored or silver line in the middle of the thermometer moves

up and down depending on the temperature. • The thermometer measures temperatures in Fahrenheit, Celsius and

another scale called Kelvin. • Fahrenheit is used mostly in the United States, and most of the rest of

the world uses Celsius. Kelvin is used by scientists.

Fahrenheit (F) – ‘murica

• Freezing point of water is 32 degrees, and boiling point is 212.• Fahrenheit is named after the German

physicist Gabriel D. Fahrenheit who developed his scale in 1724. • He arbitrarily (meaning: randomly) decided

that the difference between the freezing point and boiling point of water should be 180 degrees.

Celsius (C) – the rest of the world• Larger units than F.• Freezing point of water is 0, boiling point is 100.• The Celsius scale is named after Anders Celsius.

The Celsius scale used to be called the "centigrade" scale. Centigrade means "divided into 100 degrees." Anders Celsius developed his scale in 1742. • This scale is much more scientific because the

measurement is broken down into an even 100 degrees.

Kelvin (K) – most often used in science

• Called Kelvins • An increase of 1K is an increase of 1C.

• The freezing point is 273K, and the boiling point is 373K• The lowest temperature POSSIBLE is -273K (-

523F). No more thermal energy can be removed from matter at this point. It is called absolute zero. Molecules no longer move at this temp.

A bit about Kelvin

• Kelvin is named after Lord Kelvin, whose full name is Sir William Thomson, Baron Kelvin of Largs, Lord Kelvin of Scotland. His scale starts at 0 degrees Kelvin, which is called absolute temperature.• Lord Kelvin took the idea of temperature one step further with his

invention of the Kelvin Scale in 1848. The Kelvin Scale measures the coldest temperature there can be. He said there was no upper limit of how hot things can get, but he said there was a limit as to how cold things can get.

Thermal Energy and Heat

• The total energy of all the particles is called thermal energy (sometimes called internal energy)• Thermal energy depends on the • number of particles in the object, • temperature of the object,• and the arrangement of the object’s particles.• As thermal energy is increased, particles move faster and matter

expands.

Thermal energy and temp

• The more particles an object has at a given temperature, the more thermal energy it has. • So, a small cup of water and a large cup of

water, at the same temperature: the larger cup has more thermal energy, even though the temp is the same. • If the cups are the same size, but one has a

higher temperature, the one with the higher temperature has more thermal energy.

Heat

• Thermal energy that moving from a warmer object to a colder object.

• Like using a stove. You put a cold pot with food on a stove and turn it on. The stove provides a heat source. The stove gets hot and heats the colder object(s).

• Heat is considered energy transfer. So it is measured in joules.

Specific heat (one of my favorite things)• The amount of energy required to raise the temperature of 1 kg

(about 2.2 pounds) of a material by 1 degree Kelvin is called specific heat. • The unit is j/(kgK)• A material with high specific heat can absorb a great deal of thermal

energy without changing temp a lot. • Change in energy: mass x specific heat x change in temperature

Why is specific heat important? (could be an exam question)• For example, we live in Los Angeles.• Even though Los Angeles is a desert (meaning we don’t get a lot of

rain), we have a very nice climate. This is because we are so close to an ocean.• Water has a very high specific heat, so when temperatures go up, we

stay relatively cool (compared to other, non-coastal areas) because the water stays cool. This has a big effect on our weather system.

Please complete pg 477 1abc, 2abc, and 3a and b• https://www.youtube.com/watch?v=j9GDDLwzpAY Bill• https://www.youtube.com/watch?v=maPt__CZ1cY old video• Then we’ll learn about heat from a really old video and/or Bill

Nyw.YES. AWESOME.