Solar Cooker Data

Time Plain Insulated (oC) (oC)

0 23 222 29 304 32 366 33 408 34 4310 35 4512 35 4614 35 4716 35 47

Time Plain Insulated (oC) (oC)

18 35 4720 35 4722 35 4724 35 4726 35 47

Energy Resources

Energy is the capacity to do work.

Energy is measured in Joules

1 Joule of energy can raise 1 N of weight exactly 1 meter

1 J=1N•m

(PS: your diet offers ~5-10 million J/day)

First Law of Thermodynamics

Energy can neither be created nor destroyed. It can be converted to another form.

Energy is the capacity to do work.

Forms include:

•

•

•

•

•

•

Energy is the capacity to do work.

Forms include:

• Kinetic energy

• Potential energy

• Chemical energy

• Heat

• Elastic potential energy

• Electrical energy

Energy is the capacity to do work.

Forms include:

• Kinetic energy

• Potential energy

• Chemical energy

• Heat

• Elastic potential energy

• Electrical energy

Together, these are called “mechanical energy”

Friction converts kinetic energy to heat

Conversion of energy

Conversion of energyElectrical energy lifts cars

Conversion of energyHighest potential energy

Conversion of energyHighest kinetic energy

Conversion of energypotential kinetic

Conversion of energykinetic potential

Heat: Rule 1

• All matter is composed of particles in constant motion

Heat: Rule 2

• Temperature is a measure of the kinetic energy of the particles.

Heat: Rule 2 (a and b)

• Temperature is a measure of the kinetic energy of the particles.

a) When you heat a sample, the particles speed up

b) When you cool a sample the particles slow down

Heat: Rule 2 (a and b)

• Temperature is a measure of the kinetic energy of the particles.

a) When you heat a sample, the particles speed up

b) When you cool a sample the particles slow down

Absolute zero is the temperature at which the particles stop (-273oC)

Particles in motion:

• Solid Liquid Gas

Heat transfer

• Hot things cool and cold things warm up.

• Duh.

Heat transfer

• Hot things cool and cold things warm up.

Three ways:

1)

2)

3)

Heat transfer

• Hot things cool and cold things warm up.

Three ways:

1) Convection

2) Conduction

3) Radiation

Convection

Heat is carried up by the hotter mantle material which is less dense.

Conduction

Cold Hot

Objects in contact

Conduction

Cold Hot Not so

cold

Not so hot

Conduction

Cold Hot Not so

cold

Not so hot

Hot (fast) particles collide with cool (slow) particles. The fast ones slow down while the

slow ones speed up

Conduction

Cold Hot Not so

cold

Not so hot

Fast (hot) particles collide with slow (cool) particles. The hot ones cool down while the

cool ones warm up

Radiation

• Heat is transferred by electromagnetic radiation—visible and not-so-visible light.

Radiation

The electromagnetic spectrum

Warm objects “glow” in infrared light

Hot objects glow in visible light

Review—How can this hot object

lose heat?

Review—How can this hot object

lose heat?

Energy, Work, and Power

• Energy .

• Work

.

• Power

Energy, Work, and Power

• Energy—the capacity to do work

• Work—exerting a force over a distance

• Power—the rate of work being done

Energy, Work, and Power

• Energy—the capacity to do work

• Work—exerting a force over a distance

• Power—the rate of work being done

Work = Force x distance

Energy, Work, and Power

• Energy—the capacity to do work

• Work—exerting a force over a distance

• Power—the rate of work being done

Work = Force x distance

Energy = the amount of work done

Energy, Work, and Power

• Energy—the capacity to do work

• Work—exerting a force over a distance

• Power—the rate of work being done

Work = Force x distance

Energy = the amount of work done

Power = work / time

Energy, Work, and Power

• Energy—the capacity to do work

• Work—exerting a force over a distance

• Power—the rate of work being done

Measured in Joules

Measured in Joules

Measured in Watts

Energy, Work, and Power

• Energy—the capacity to do work

• Work—exerting a force over a distance

• Power—the rate of work being done

Measured in J, kJ, cal, kcal, ft-lb, BTU, Q, kWh

Measured in W, hp, ft-lb/s

Measured in J, kJ, cal, kcal, ft-lb, BTU, Q, kWh

U&A Question 5

• 300 hp=300 x (550 ft-lb/s) =165000 ft-lb/s!

• This motor could lift 165000 lbs at a rate of 1 ft/s

(or)

• 16500 lbs (a freight elevator) at 100 ft/s

How do you get energy to do work?

To generate electricity…

How would you like to heat your

water?

Second Law of Thermodynamics

When energy converted to another form, some of the energy is lost as unusable heat.

Second Law of Thermodynamics

When energy converted to another form, some of the energy is lost as unusable heat.

(or)

Energy conversion is never 100% efficient.

Electricity

• A generator generates electricity.

• Work done on the generator is converted to electrical energy

• You do work on the generator by turning the crank.

What turns your crank?

• A turbine converts kinetic energy of a fluid into rotation.

• Most electricity is made by steam driving a turbine

To generate electricity…

How would you like to heat your

water?

Options for turning a turbine

Heatsteam

•

•

•

•

•

•

Options for turning a turbine

Heatsteam

• Coal

• Natural gas

• Nuclear fission

• Biomass

• Solar

• Ocean thermal

Options for turning a turbine

Heatsteam Direct

• Coal 1)

• Natural gas 2)

• Nuclear fission 3)

• Biomass

• Solar

• Ocean thermal

Options for turning a turbine

Heatsteam Direct

• Coal 1) Hydroelectric

• Natural gas 2) Wind

• Nuclear fission 3) Tidal

• Biomass

• Solar

• Ocean thermal

Options for turning a turbine

Heatsteam Direct

• Coal 1) Hydroelectric

• Natural gas 2) Wind

• Nuclear fission 3) Tidal

• Biomass

• Solar

• Ocean thermal

Someday, nuclear fusion?

Photovoltaic cells

• Photovoltaic (PV) cells convert light directly to electrical energy (no generator).

Electrical generation

Energy coming in

Energy lost

Energy provided as electricity

First Law of Thermodynamics

• Energy is never created nor destroyed

(See Slide 1)

• Matter is never created nor destroyed

• They can be converted into each other.

Global Carbon Cycle

Carbon Cycle

• Where is the carbon?

1)

2)

3)

4)

Carbon moves from one form to another.

Carbon Cycle

• Where is the carbon?

1) In fossil fuels and minerals

2) Living systems

3) Oceans

4) Atmosphere

Carbon moves from one form to another.

Who cares?

• Natural systems maintain the balances.

• Anthropogenic (man-made) carbon flow comes from living systems and fossil fuels to the atmosphere

• Greenhouse gasses (CO2 and methane in the atmosphere) contribute to global warming.

Acid Rain

• Burning fossil fuels contributes to acid rain

• Acid rain affects fish, amphibians, plants & surface water.

• Limestone neutralizes some of the acidity.

pH• pH measures

acidity

• pH<7 is acidic

• pH>7 is basic

• pH=7 is neutral

• (see p R48)

• (Acid rain has pH 5.1-4.3 or less)

Oil

Petroleum: from petro- “rock” & –oleum “oil”

Crude oil—(from the well) is distilled into:

• Natural gas

• Gasoline

• Kerosene

• Diesel

• Fuel oil

• Asphalt

From lowest to highest

boiling point

Oil Use

Oil became:

--the fastest growing energy resource in 1920

--the greatest used energy resource in 1950

The US:

• --uses about 20,000,000 barrels of oil per day (about 1/5 of the world total)

• --produces about 5,000,000 barrels of oil/day (about 1/17 of world total)

An oil reservoir

An oil reservoir

Drill here.

Solar and Wind Power

• See “Digging Deeper” in activity 8