PHYSICAL SCIENCE Temperature and Heat

1. PHYSICAL SCIENCETemperature and Heat Chapter 5-part 2

2. Temperature • Heat and temperature are related but they are not the same thing. • All matter is in constant motion. Think about the motion of particles. All matter has moving particles (atoms). Ex. The table, your shoe, etc. • All moving things have Kinetic energy (KE). • The faster particles move, the more KE they have. • Temperature is the measure of the average KE of the particles in a sample of matter. • As particles move faster, the temperature increases.

3. Thermal Energy • This is the total energy of the atoms in a material. This total includes both potential energy (PE) and KE. Temperature only measures the average KE of the atoms. • Ex. Ice cream and hot spoon p. 135 The hot spoon isn’t moving. The melting of the ice cream is caused by the flow of thermal energy from the spoon to the ice cream. The KE is from the vibrations between and within the atoms in the spoon, the PE is from the forces that act within or between these atoms.

4. Which has more thermal energy 10,000 4 kg lead weights

5. Heat • The thermal energy that flows from something with a higher temperature to something with a lower temperature. So heat flows from warmer objects to cooler objects. • Ex. Which way would heat flow if you placed your warm hand on the cool desk? • Ex. Put an ice cube in a warm drink. Which way is the heat flowing?

6. Thermal Pollution • What is it? • When waste heat significantly changes the temperature of the environment. • What kind of things release heat into the air? • What kind of things release heat into the waters (oceans, streams, lakes)?

7. How Do We Measure Thermal Energy? • Specific Heat- the amount of energy it takes to raise the temperature of 1 kg of a material by 1 Kelvin. • Specific Heat is measured in J/(kg • K) • Different materials have different specific heats. Ex. Water = 4184 J/(kg • K) Aluminum = 920 J/(kg • K) Which one takes more energy to raise it’s temperature?

8. Heat Absorption • Water and other materials with a high specific heat can absorb a lot of heat without changing temperature much. • Ex. Swimming pool does not heat up after one hot day- it takes a month of hot days to warm the water. • The specific heat of a material has to do with the way it’s atoms are arranged.

9. Calculating Thermal Energy • We don’t have an instrument to measure changes in thermal energy, but we can calculate it mathematically. Yaaa! • Ex. If I heat up a piece of metal and drop it into a cup of water, I can assume that the temperature increase in the water was caused by the cooling of the metal. • Other factors to consider: How much heat is lost to the cup and the air above the water?

10. Q = m • ΔT • C Q = Change in thermal energy m = mass ΔT = change in temperature (final – initial) C = Specific heat Ex. A 32-g silver spoon cools from 60° to 20° C. What is the change in thermal energy? Specific heat of silver is 0.23 J/Kg K. Convert grams to Kg Convert Celsius to Kelvin (add 273) (.032 Kg) (313K) (0.23 J/Kg K)= 2.3 J

11. Homework • Day 1: Read pp. 134-146 • Day 2: Rev. Vocab. #4-7, 9,10 • Day 3: Check. Concepts: #3,4,7,10 • Day 4: Under. Concepts: #14, 19 (use chart on p. 141 to get specific heat of copper and water) • Day 5: Finish Lab #7 “Specific Heat Capacity” • Study for and take Ch. 5 test. Test due dates: EIE: Nov. 6th, CCPC: Nov. 8th

12. Study Sheet for Ch. 5 test Know the following terms: Energy, specific heat, heat, temperature, kinetic energy, thermal energy, law of conservation of energy, thermal pollution, mechanical energy, work, potential energy, work. Know how to calculate work and changes in thermal energy. Formulas: W = f X d Q = m XΔT X C