1. CHAPTER 15:
ENERGY!

2. RESOURCES Vocabulary Review: Quizlet Ch 15
Doodle Science Playlist: High School Physics

3. Energy: Measured in joules!
The ability to do work
Work = Force x distance
Measured in joules!

4. ENERGY

5. Forms of Energy: Kinetic: energy of movement (depends on
mass and velocity)

6. Forms of Energy: Potential: energy of position
- gravitational: depends on mass, height
and acceleration due to gravity
- elastic: depends on ability to be
stretched or compressed
- chemical: stored in bonds
- electrical: associated with charge
- nuclear: stored in the atomic nucleus
- electromagnetic: waves (light/rays/sound)

7. The Law of Conservation
of Energy
Energy is never created or destroyed – it is
transformed from one form to another.
(PE+KE)Beginning = (PE+KE)End

8. The Law of Conservation
of Energy
Often, kinetic energy will be transformed into
thermal energy, via FRICTION.
This is the reason we always LOSE efficiency
when work is done!

9. Calculating Kinetic Energy
m = mass (kg)
v = velocity (m/s)
KE = kinetic energy (Joules)

10. Calculating Kinetic Energy
What is the kinetic energy of a 75-kg student
running at a speed of 3 m/s?

11. A. Energy ENERGY ENERGY THERMAL The ability to cause change.
internal motion of particles
ENERGY
MECHANICAL
NUCLEAR
ENERGY
motion of objects
changes in the nucleus
ELECTRICAL
joules (J)
CHEMICAL
motion of electric charges
bonding of atoms

12. Calculating Potential Energy
m = mass (kg)
g = acceleration due to gravity (9.8 m/s2)
h = height (m)
PE = potential energy (Joules)

13. Calculating Potential Energy
A mover carries a television with a mass of 62 kg
a distance of 18 m up the stairs. How much
potential energy does the TV have?
PE = (62)(9.8)(18)
= 10,937 J

14. The Law of Conservation
of Energy
If 2500-kg roller coaster car begins its descent from
500 m above the first hill, what is its kinetic energy at
the bottom of that hill?
PE = (2500)(9.8)(500) = 12,250,000 J = KE!

16. Energy and Work Work & Energy Conservation of Energy
Ch Energy
Energy and Work
Work & Energy
Conservation of Energy

17. A. Energy ENERGY ENERGY THERMAL The ability to cause change.
internal motion of particles
ENERGY
MECHANICAL
NUCLEAR
ENERGY
motion of objects
changes in the nucleus
ELECTRICAL
joules (J)
CHEMICAL
motion of electric charges
bonding of atoms

18. A. Energy Kinetic Energy (KE) Which has the most KE? 80 km/h truck
energy in the form of motion
depends on mass and velocity
80 km/h
50 km/h
Which has the most KE?
Which has the least KE?
80 km/h truck
50 km/h motorcycle

19. A. Energy Potential Energy (PE)
stored energy
depends on position or configuration of an object
Which boulder has greater gravitational PE?
What other ways can an object store energy?

20. W = Fd B. Work W: work (J) F: force (N) d: distance (m) 1 J = 1 N·m
transfer of energy through motion
force exerted through a distance
W = Fd
W: work (J)
F: force (N)
d: distance (m)
1 J = 1 N·m
Distance must be in direction of force!

21. B. Work
Brett’s backpack weighs 30 N. How much work is done on the backpack when he lifts it 1.5 m from the floor to his back?
GIVEN:
F = 30 N
d = 1.5 m
W = ?
WORK:
W = F·d
W = (30 N)(1.5 m)
W = 45 J F W d

22. B. Work d W F GIVEN: m = 40 kg d = 1.4 m - during d = 2.2 m - after
A dancer lifts a 40 kg ballerina 1.4 m in the air and walks forward 2.2 m. How much work is done on the ballerina during and after the lift?
GIVEN:
m = 40 kg
d = 1.4 m - during
d = 2.2 m - after
W = ?
WORK:
W = F·d F = m·a
F =(40kg)(9.8m/s2)=392 N
W = (392 N)(1.4 m)
W = 549 J during lift
No work after lift. “d” is not in the direction of the force. F W d

23. C. Conservation of Energy
Law of Conservation of Energy
Energy may change forms, but it cannot be created or destroyed under ordinary conditions.
EX: ENERGY CONVERSIONS
PE  KE
mechanical  thermal
chemical  thermal

24. C. Conservation of Energy
PE  KE
View pendulum animation.
View roller coaster animation.

25. C. Conservation of Energy
Mechanical  Thermal
View rolling ball animations.
View skier animation.

28. Energy and MASS
E=mc2
E: energy (J)
M: mass (kg)
C: speed of light (3.0X 108 m/s)
Einstein showed that mass and energy are equivalent and can be converted into each other.

29. Energy and MASS
E=mc2
E: energy (J)
M: mass (kg)
C: speed of light (3.0X 108 m/s)
How much energy is released if 1 gram of matter is completely converted into energy?

30. Energy Resources History of Human Energy Use: CC 7 min.
Non-renewable Energy Resources: Doodle
Renewable Energy Resources: Doodle 1 & Doodle 2
Energy  National Grid

31. Writing/Drawing Assignment
YOUR TURN TO DOODLE 
Writing/Drawing Assignment
On a piece of paper draw & LABEL:
A building with a purpose of your choice
(i.e. gym/school/house, etc.)
Must use 4 types of Energy Resources
Strive for a sustainable design.
Write a paragraph about your building:
What is its purpose?
How does the design conserve energy?
What energy resources does it use?
Is this practical? Could you market this design? Why or Why not?

32. HEAT – Thermal Energy Transfer
Ch & Thermodynamics
Kinetic Theory – energy determines state of matter
What is heat?
Transfer of thermal energy from one object to another
Heat Transfer -
Conduction & Convection
Radiation
What is temperature?
Measure of heat compared to a reference point (degrees)

35. Kinetic Energy Practice Problems
What is the Kinetic Energy of a 150 kg object that is moving with a speed of 15 m/s?
An object has a kinetic energy of 25 J and a mass of 34 kg , how fast is the object moving?
An object moving with a speed of 35 m/s and has a kinetic energy of 1500 J, what is the mass of the object.
What is the Kinetic Energy of a 1200 kg object that is moving with a speed of 24 m/s?
An object has a kinetic energy of 14 J and a mass of 17 kg , how fast is the object moving?
An object moving with a speed of 67 m/s and has a kinetic energy of 500 J, what is the mass of the object.
What is the Kinetic Energy of a 478 kg object that is moving with a speed of 15 m/s?
An object has a kinetic energy of 88 J and a mass of 45 kg , how fast is the object moving?
An object moving with a speed of 21 m/s and has a kinetic energy of 140 J, what is the mass of the object.
What is the Kinetic Energy of a 100 kg object that is moving with a speed of 12.5 m/s?

36. An object has a kinetic energy of 14 J and a mass of 17 kg , how fast is the object moving?