B3.3 and B3.4

1. B3.3 and B3.4 Useful Energy, Efficiency and Energy Applications

2. We use machines to convert the energy added to it (energy input) to a different form of energy (useful energy output) that we may want to do work (useful work output). A system will always lose some energy as wasted heat. In other words, the useful energy input is never equal to the useful energy output. A perfect machine, which is 100% efficient in converting energy, is only theoretical.

3. Efficiency Efficiency is a measurement of how effectively a machine converts input energy into useful energy output. This gives us the efficiency as a decimal between 0 and 1. Efficiency is sometimes expressed as a percent.

4. examples: Practice Problems p. 216 1) In lifting a car, the total mechanical energy input of a hydraulic hoist is 5.61 x 104 J, while the useful mechanical energy output is 1.96 x 104 J. Calculate the percent efficiency of the hoist. 34.9 % 2) A small electric motor has an efficiency of 85%. In lifting a small load, it produces 15 J of mechanical energy input. Calculate the useful mechanical energy output of the motor. 13 J 3) A Bunsen burner supplies 4.00 x 103 J of heat to a small beaker of water. Only 125 J of heat is gained by the beaker and water. Calculate the percent efficiency of the burner. 3.13 %

5. For this section you will be creating your own notes by completing the following tasks – Space is allotted in your notepack: • The primary energy source for life on earth is the ______________. • Define solar energy sources and provide examples. • Define non-solar energy sources and provide examples. • Distinguish between renewable an non-renewable resources and provide examples of each. • The most important source of energy in industrial societies is ____________. • List the three factors that have placed dangerous demands on our energy supplies. • Name 2 negative effects of our dependence on fossil fuels. • List 3 ways that we can maintain sustainable development.

6. Energy Applications Answers: 1. The primary energy source for life on earth is the 2. Define solar energy sources and provide examples. SUN Solar energy sources are those that are derived from the energy of the sun. Examples include wind energy, water energy, biomass (organic matter) and fossil fuels.

7. Non-solar energy sources have NO relationship with the sun. Examples include: Nuclear energy, geothermal energy, and tidal energy 3.Define non-solar energy sources and provide examples. 4. Distinguish between renewable an non-renewable resources and provide examples of each. Renewable energy sources are continually and infinitely available. Examples include solar, wind, water, geothermal, tidal and biomass Non Renewable energy sources are those that are limited and irreplaceable. Examples include nuclear and fossil fuels.

8. electricity 5. The most important source of energy in industrial societies is 6. List the three factors that have placed dangerous demands on our energy supplies. 7.Name 2 negative effects of our dependence on fossil fuels. • The amount of energy consumed per person has increased exponentially • The population has grown exponentially • Societies are using nonrenewable resources as the primary source of energy • It has put a strain on our existing supplies • It has been detrimental to our environment

9. USE LESS!!!!!! • Cogeneration: Use the waste energy from one process to power a second • Increase efficiency 8. List 3 ways that we can maintain sustainable development.

10. HOMEWORK • Section 3 Review page 228 #’s1-20 • Prepare for Physics Unit Exam • Complete Unit B Review page 232-235