Question of the Day Rules

• You must work alone• You may use your textbook today• You have 6 minutes to complete the

QOD

Good luck!!

Questions of the Day

2) Sani bought a new camel and wants to know the energy efficiency. The camel consumes 350 Joules of energy, but only does 50 Joules of work (lazy). What is the energy efficiency of the camel?

  

1) Is it more energy-efficient to let a lightbulb burn for a short period of time, or to turn it off and then on again?

Answers.

Answer: It is more energy efficient to turn the light off than to leave it on. Energy is measured with respect to time. The momentary or millisecond or less surge of electricity required to start your light bulb will not impact your energy cost, but leaving it on all the time will.

1) Is it more energy-efficient to let a lightbulb burn for a short period of time, or to turn it off and then on again?

Answers2) Mr. Meades bought a new camel and wants to know the energy efficiency. The camel consumes 350 Joules of energy, but only does 50 Joules of work. What is the energy efficiency of the camel?

What are we doing Today?• Hand in lab on ppm• Question(s) of the day• Ch. 3 – notes• Get back ICEPAC• Workbook p.39-40• Horse Race

• Energy is the ability to do work or effect change (p. 71).

• Energy transfer is the movement of energy from one

place to another (p. 71).

Energy TransferExamples:

1)Roasting marshmallows with a wire. Conduction transfers energy as heat along the wire and into the hand.

Energy transformation is the changing of energy from one form

to another (p. 71).

Energy Transformation

Examples:

1) A lightbulb, where electrical energy is transformed into light energy

• The law of conservation of energy: says that energy is neither created nor destroyed. When we use energy, it doesn’t disappear. We change it from one form of energy into another.

Energy Efficiency

• Energy Efficiency is the amount of useful energy you get from a system.

• Converting one form of energy into another

form always involves a loss of usable energy.

Example of Energy Efficiency

• In fact, most energy transformations are not very efficient. The human body is a good example. Your body is like a machine, and the fuel for your machine is food. Food gives you the energy to move, breathe, and think. But your body isn’t very efficient at converting food into useful work. Your body is less than five percent efficient most of the time. The rest of the energy is lost as heat. You can really feel that heat when you exercise!

Energy Efficiency

Energy Efficiency Question

• To perform work equal to 2 400 J, a machine consumes 12 000 J. What is the energy

efficiency of this machine?

To perform work equal to 2 400 J, a machine consumes 12 000 J. What is the energy

efficiency of this machine?

• Thermal energy is the energy contained in a substance, determined by the number of particles in the substance and their temperature (p. 73).

Thermal energy is the energy contained in a substance, determined by the number of particles in the substance and their temperature (p. 73).

• Heat: is the transfer of thermal energy between two environments with different temperatures. Heat always passes from the warmer to the cooler environment (p. 73).

Question ?

• If a cup of coffee and a red popsicle were left on the table in this room what would happen to them? Why?

• The cup of coffee will cool until it reaches room temperature. The popsicle will melt and then the liquid will warm to room temperature.

• Temperature: is a measure of the degree of agitation of the particles of a substance (p. 74).

Chemical Energy

• Stored chemical energy is released in the form of thermal energy when it is burned.

Electrical Energy• Electricity

– Example: hydro-electric dams – falling water is changed to electrical energy

Geothermal Energy• Energy that we get from the Earth’s interior

Solar Energy

• Energy from the sun

Wind Energy

• Moving air• Is a result of solar

energy – as the sun heats the air, the warmer air rises and cools off. Cooler air falls, creating a convection current – this forms wind

Fossil Fuels

• Chemicals made from plants and animals that died and decomposed millions of years ago and have preserved deep underground.

ClassWork

1) Complete P.39-40 in your workbook.

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