Competency Goal 3: The learner will analyze energy and its conservation.

Objectives 3.01 Investigate and analyze storage of energy:•Kinetic energy. •Potential energies: gravitational, chemical, electrical, elastic, nuclear. •Thermal energy.3.02 Investigate and analyze transfer of energy by work:•Force. •Distance.3.03 Investigate and analyze transfer of energy by heating:•Thermal energy flows from a higher to a lower temperature. •Energy will not spontaneously flow from a lower temperature to a higher temperature. •It is impossible to build a machine that does nothing but convert thermal energy into useful work.3.04 Investigate and analyze the transfer of energy by waves:•General characteristics of waves: amplitude, frequency, period, wavelength, velocity of propagation. •Mechanical waves. •Sound waves. •Electromagnetic waves (radiation).

Potential vs. Kinetic Energy

• Potential Energy—energy of position or condition.

•PEg = mgh = Fgh• Kinetic Energy—energy of motion.

•KE = ½ mv2

• Mechanical Energy—Total PE + KE– ALWAYS REMAINS CONSTANT!!!

Where is PE the greatest? Least?Where is KE the greatest? Least?

Work vs. Power• Work—transfer of energy through motion– 1. Object must move.– 2. Movement must be in direction of the applied force.

W = Fd• Power—time rate of doing work!!

P = W/t**May need to find work in order to find

Power!!**If you are lifting an object, force required is

equal to the weight of the object(not the mass!!)

Heat Energy• Specific Heat—Amount of heat required to

change the temperature of a substance!!–Different for all substances!!!–Metal heats faster than wood, but also cools

faster!!!– Low specific heat= heat up fast, cool down

fast!!–High specific heat= heat up slow, cool down

slow!!

Heat Energy(cont.)

• Heat energy always flows from High temperature substance to low temperature substance!!!

• When you add heat to a substance, one of two things will happen, but never at the same time:1. Substance changes temperature!!2. Substance changes phase!!

What phase of matter is found on the “Red” part of graph?

What phase of matter is found on the “Red” part of graph?

What phase of matter is found on the “Red” part of graph?

What phase of matter is found on the “Red” part of graph?

What phase of matter is found on the “Red” part of graph?

What type of change is occurring at the “Red” part of graph?

What type of change is occurring at the “Red” part of graph?

What type of change is occurring at the “Red” part of graph?

What type of change is occurring at the “Red” part of graph?

What type of change is occurring at the “Red” part of graph?

What is the Melting Point of this substance?

25 oC

90 oC

What is the Boiling Point of this substance?

25 oC

90 oC

Phase

Phase

T

T

T

Solid

Liquid

GasBoiling Pt.

Melting Pt.

3 Ways to Transfer Heat1. Conduction---direct contact

2. Convection—transfer of heat in liquids and gases!!

3. Radiation—transfer through empty space!!

Waves• Waves transfer ENERGY, not matter!!

Wave Properties(cont.)

• Frequency is # waves per time!!• Frequency is related to pitch!!• Amplitude is related to amount of energy!!– Taller waves carry more energy!!– Smaller waves carry less energy!!!

• Velocity = frequency x wavelength

vw = f

Electromagnetic Spectrum• The spectrum is on your formula sheet.– Wavelength is shown.– Must be able to answer questions about frequency and

amount of energy, also.– If all electromagnetic waves travel at the speed of light,

remember the relationship between wave velocity, frequency, and wavelength.

– As the wavelength get longer, the frequency and amount of energy gets smaller.

– As the wavelength gets shorter, the frequency and amount of energy gets higher.

Electromagnetic Spectrum(measurement in meters)

Longer Wavelength Shorter Wavelength

Radiowaves

Microwaves

Infrared Ultraviolet

10 4 10 3 10 2 10 1 10 0 10 –1210 –1110 –1010 –910 –710 –610 –510 –410 –310 –210 –1 10 –8

Gammarays

X rays

Red Orange Yellow Green VioletBlue

Visible Light

4.010–74.210–74.910–75.710–75.910–76.510–77.010–7

10 –13

What waves have the longest wavelength?What waves have the shortest wavelength?

Electromagnetic Spectrum(measurement in meters)

Longer Wavelength Shorter Wavelength

Radiowaves

Microwaves

Infrared Ultraviolet

10 4 10 3 10 2 10 1 10 0 10 –1210 –1110 –1010 –910 –710 –610 –510 –410 –310 –210 –1 10 –8

Gammarays

X rays

Red Orange Yellow Green VioletBlue

Visible Light

4.010–74.210–74.910–75.710–75.910–76.510–77.010–7

10 –13

What waves have the highest frequency?What waves have the lowest frequency?

Electromagnetic Spectrum(measurement in meters)

Longer Wavelength Shorter Wavelength

Radiowaves

Microwaves

Infrared Ultraviolet

10 4 10 3 10 2 10 1 10 0 10 –1210 –1110 –1010 –910 –710 –610 –510 –410 –310 –210 –1 10 –8

Gammarays

X rays

Red Orange Yellow Green VioletBlue

Visible Light

4.010–74.210–74.910–75.710–75.910–76.510–77.010–7

10 –13

What waves carry the most energy?What waves carry the least energy?