1. Energy!!!Energy!!!

2. The Law of Conservation ofThe Law of Conservation of
EnergyEnergy
Energy cannot be created orEnergy cannot be created or
destroyed; it may be transformeddestroyed; it may be transformed
from one form into another, but thefrom one form into another, but the
total amount of energy nevertotal amount of energy never
changes.changes.

3. ““the ability to do work”the ability to do work”
The combination of energy andThe combination of energy and
matter make up the universe:matter make up the universe:
– Matter is substance, and energy isMatter is substance, and energy is
the mover of substance.the mover of substance.
What is energy?What is energy?

4. Energy isEnergy is
nature’s way of keeping score.nature’s way of keeping score.
We sense energyWe sense energy
only when theonly when the
score changes,score changes,
either aeither a
transformationtransformation
from one form offrom one form of
energy to another,energy to another,
or a transfer ofor a transfer of
energy from oneenergy from one
point to another.point to another.

5. How is all energy divided?How is all energy divided?
Potential
Energy
Kinetic
Energy
All Energy
Gravitation
Potential
Energy
Elastic
Potential
Energy
Chemical
Potential
Energy

6. Potential KineticPotential Kinetic
energy ofenergy of
position orposition or
energy inenergy in
storage.storage.
– Water behind aWater behind a
damdam
– Hammer over headHammer over head
– Food on the plateFood on the plate
energy ofenergy of
motion, the formmotion, the form
capable of doingcapable of doing
workwork
– Flowing waterFlowing water
– A falling hammerA falling hammer
– ElectronsElectrons
regenerating ATP inregenerating ATP in
a bio’l cella bio’l cell

7. PE = mghPE = mgh
m = massm = mass
(kg)(kg)
h = heighth = height
(m)(m)
g = accel dueg = accel due
to gravityto gravity
–(9.8 m/s(9.8 m/s22
))

8. What is Gravitational PotentialWhat is Gravitational Potential
Energy?Energy?
o Potential energyPotential energy
due to an object’sdue to an object’s
positionposition
o P.E. = mass xP.E. = mass x
height x gravityheight x gravity
Don’t look down,
Rover!
Good boy!

9. What is Potential Energy?What is Potential Energy?
o Energy that is storedEnergy that is stored
and waiting to beand waiting to be
used laterused later

10. What is Elastic Potential Energy?What is Elastic Potential Energy?
o Potential energy due compression orPotential energy due compression or
expansion of an elastic object.expansion of an elastic object.
Notice the ball compressing
and expanding

11. What is Chemical Potential Energy?What is Chemical Potential Energy?
o Potential energyPotential energy
stored within thestored within the
chemical bonds ofchemical bonds of
an objectan object

12. What is Kinetic Energy?What is Kinetic Energy?
o Energy an object has dueEnergy an object has due
to its motionto its motion
o K.E. = .5(mass x speedK.E. = .5(mass x speed22
))

13. KE = 1/2 m vKE = 1/2 m v22
4 kg bowling4 kg bowling
ballball
at 10 m/sat 10 m/s
= .5 (4kg)= .5 (4kg)
(10m/s)(10m/s)22
= 200 J= 200 J
.25 kg baseball.25 kg baseball
at 50 m/sat 50 m/s
= .5 (.25kg) (50= .5 (.25kg) (50
m/s)m/s)22
= 312 J= 312 J

14. Courtesy Jerry Ohlinger’s Movie Material Store
Work is done when a force is exerted over a distance.

15. WorkWork
is equal to the force that is exertedis equal to the force that is exerted
times the distance over which it istimes the distance over which it is
exerted.exerted.
W = F x dW = F x d
The unit of work combines theThe unit of work combines the
unit of force (N) with the unit ofunit of force (N) with the unit of
distance (m)distance (m)
Newton-meter (N-m) aka Joule.Newton-meter (N-m) aka Joule.

16. You carry aYou carry a 20 kg suitcase20 kg suitcase upstairs, aupstairs, a
distance of 4mdistance of 4m. How much work did you. How much work did you
do?do?
W = F x dW = F x d
F = maF = ma
= (20 kg) (10m/s= (20 kg) (10m/s22
) = 200 N) = 200 N
W = F x dW = F x d
= (200 N) (4m)= (200 N) (4m)
= 800 J= 800 J

17. PowerPower
measures the rate of work done.measures the rate of work done.
or the rate at which energy isor the rate at which energy is
expended.expended.
Power is the amount of workPower is the amount of work
done, divided by the time it takesdone, divided by the time it takes
to do it.to do it.
Power (watts) = work (joules) /Power (watts) = work (joules) /
time (sec)time (sec)
P = W/tP = W/t

18. PowerPower
Since work performed equals energySince work performed equals energy
expended,expended,
Power (watts) = energyPower (watts) = energy
(joules) / time (sec)(joules) / time (sec)
The watt is defined as theThe watt is defined as the
expenditure ofexpenditure of
1 joule of energy in 1 second.1 joule of energy in 1 second.
(75 watt light bulb consumes 75(75 watt light bulb consumes 75
J/sec)J/sec)

19. Important formulas and unitsImportant formulas and units
QuantityQuantity DefinitionDefinition UnitsUnits
ForceForce mass x accel.mass x accel. newtonsnewtons
WorkWork force x distanceforce x distance joulesjoules
EnergyEnergy power x timepower x time joulesjoules
PowerPower work / timework / time wattswatts

20. Ex. Problem on Power:Ex. Problem on Power:
Your CD system, uses 250 watts ofYour CD system, uses 250 watts of
electrical power.electrical power.
You play it for 3 hrs. How muchYou play it for 3 hrs. How much
energy used? About how much wouldenergy used? About how much would
it cost?it cost? If one kWh is $.08.If one kWh is $.08.
Energy (J) = power (watts) x timeEnergy (J) = power (watts) x time
(sec) = (250w) (3hr) = 750 Whr = .(sec) = (250w) (3hr) = 750 Whr = .
75 kWh75 kWh
The cost = 8 cents/ kWh x .75 kWhThe cost = 8 cents/ kWh x .75 kWh
= 6 cents= 6 cents

21. 6 fundamental forms of energy6 fundamental forms of energy
1.1. mechanical energymechanical energy
2.2. Thermal (heat) energyThermal (heat) energy
3.3. electromagnetic energyelectromagnetic energy
4.4. electrical energyelectrical energy
5.5. nuclear energynuclear energy
6.6. chemical energychemical energy

22. What is the source of ourWhat is the source of our
energy?energy?
The source ofThe source of
practically allpractically all
our energy isour energy is
the Sunthe Sun..

23. What is Mechanical Energy?What is Mechanical Energy?
o Energy due to anEnergy due to an
object’s motionobject’s motion
(kinetic) or position(kinetic) or position
(potential).(potential).
The bowling ball hasThe bowling ball has
mechanical energy.mechanical energy.
When the ball strikesWhen the ball strikes
the pins, mechanicalthe pins, mechanical
energy is transferredenergy is transferred
to the pins!to the pins!

24. Examples of Mechanical EnergyExamples of Mechanical Energy

25. What is ElectromagneticWhat is Electromagnetic
Energy?Energy?
o Light energyLight energy
o Includes energy fromIncludes energy from
gamma rays, xrays,gamma rays, xrays,
ultraviolet rays,ultraviolet rays,
visible light, infraredvisible light, infrared
rays, microwave andrays, microwave and
radio bandsradio bands

26. What is Electrical Energy?What is Electrical Energy?
o Energy caused byEnergy caused by
the movement ofthe movement of
electronselectrons
o Easily transportedEasily transported
through power linesthrough power lines
and converted intoand converted into
other forms ofother forms of
energyenergy

27. What is Chemical Energy?What is Chemical Energy?
o Energy that isEnergy that is
available for releaseavailable for release
from chemicalfrom chemical
reactions.reactions.
The chemical bonds inThe chemical bonds in
a matchstick storea matchstick store
energy that isenergy that is
transformed intotransformed into
thermal energy whenthermal energy when
the match is struckthe match is struck..

28. Examples of Chemical EnergyExamples of Chemical Energy

29. What is Thermal Energy?What is Thermal Energy?
o Heat energyHeat energy
o The heat energy of anThe heat energy of an
object determines howobject determines how
active its atoms are.active its atoms are.
A hot object is one whose atomsA hot object is one whose atoms
and molecules are excitedand molecules are excited
and show rapid movement.and show rapid movement.
A cooler object's molecules andA cooler object's molecules and
atoms will show lessatoms will show less
movementmovement..

30. QUIZ TIME!QUIZ TIME!
What type of energyWhat type of energy
cooks food in acooks food in a
microwave oven?microwave oven?
ELECTROMAGNETICELECTROMAGNETIC
ENERGYENERGY
What type of energy isWhat type of energy is
the spinning platethe spinning plate
inside of a microwaveinside of a microwave
oven?oven?
MECHANICAL ENERGY

31. QUIZ TIME!QUIZ TIME!
Electrical energy isElectrical energy is
transported to your housetransported to your house
through power lines.through power lines.
When you plug an electric fanWhen you plug an electric fan
to a power outlet, electricalto a power outlet, electrical
energy is transform intoenergy is transform into
what type of energy?what type of energy?
MECHANICAL ENERGYMECHANICAL ENERGY

32. QUIZ TIME!QUIZ TIME!
What energy transformationWhat energy transformation
occurs when an electric lampoccurs when an electric lamp
is turned on?is turned on?
ELECTRICAL ENERGYELECTRICAL ENERGY
↓↓
ELECTROMAGNETIC ENERGYELECTROMAGNETIC ENERGY

33. What types of energy are shown below?What types of energy are shown below?
Mechanical and Thermal EnergyMechanical and Thermal Energy
((Don’t forget frictionDon’t forget friction))

34. What type of energy is shown below?What type of energy is shown below?
Chemical EnergyChemical Energy

35. What types of energy are shown below?What types of energy are shown below?
Electrical, Mechanical andElectrical, Mechanical and
Electromagnetic EnergyElectromagnetic Energy

36. What type of energy is shown below?What type of energy is shown below?
Chemical Energy (yummy)Chemical Energy (yummy)

37. What type of energy is shown below?What type of energy is shown below?
Thermal EnergyThermal Energy

38. What types of energy are shown below?What types of energy are shown below?
Mechanical, Electromagnetic,Mechanical, Electromagnetic,
Electrical, Chemical and ThermalElectrical, Chemical and Thermal
EnergyEnergy

39. The Law of Conservation ofThe Law of Conservation of
EnergyEnergy
Energy cannot be created orEnergy cannot be created or
destroyed; it may be transformeddestroyed; it may be transformed
from one form into another, but thefrom one form into another, but the
total amount of energy nevertotal amount of energy never
changes.changes.