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CHAPTER 5
“Energy”
Section 1 – The Nature of Energy
I. What is ENERGY?
A) Definition – the ability to do ____________.
1) Work is done when a ____________ causes something to move.
2) Alternate definition – the ability to cause ____________.
3) Example  A baseball breaking through a window (see Figure 1)
B) ____________ of Energy:
1) THERMAL – also known as ____________ energy
2) ____________ – found in food for the body to use
3) ELECTRICAL – used to operate your television or toaster
4) ____________ – also known as light energy (e.g., the sun)
5) NUCLEAR – found in the nuclei of ____________
6) Others include: MAGNETIC, SOUND, MECHANICAL, and
GRAVITATIONAL
C) An energy ____________  energy and money
II. ____________ Energy (KE)
A) Definition – the energy a moving object has because of its ____________.
B) The amount of KE depends on:
1) ____________ &
2) ____________
C) Calculating KE:
KE = ½ mv2
D) The SI unit of energy is the ____________ (J)
III. ____________ Energy (PE)
A) Definition – ____________ energy due to its position.
B) Three types of PE:
1) ____________ Potential Energy – energy stored by something that can
Stretch or compress (e.g., a rubber band or spring)
2) ____________ Potential Energy – energy stored in chemical bonds
3) ____________ Potential Energy (GPE) – stored energy by objects due to
their position above the Earth’s surface.
C) Calculating GPE:
GPE = mgh
1) GPE increases as the ____________ increases.
Section 2 – Conservation of Energy
I. Energy ____________ – changing one form of energy into other forms of energy.
A) Some energy transformations are less obvious because they do not result in visible
motion, sound, heat, or light.
B) One form of energy can be transferred into ____________ other forms of energy.
II. Conversions between ____________ and ____________ energy
A) ____________ energy
1) Definition – the total amount of PE and KE in a system
2) Calculating mechanical energy:
Mechanical energy = PE + KE
B) Potential energy is ____________ into kinetic energy and
vice-versa.
C) Application:
1) ____________ objects
2) ____________ motion
3) A ____________ or swing (as you might see at COSI)
III. The Law of ____________ of Energy
A) Energy cannot be ____________ or ____________.
B) The total amount of energy in the universe does not ____________.
C) Energy can change from one form to another, but the total amount of energy never
changes.
D) The effect of ____________ on energy: (using the example of a swing)
1) Friction and air resistance cause some of the mechanical energy to change to
____________ energy.
2) The total amount of energy always stays the ____________.
E) Nuclear ____________ and ____________
1) Nuclear fusion – a reaction in which two or more atomic nuclei form a
nucleus with a larger mass (this occurs on the ____________)
2) Nuclear fission – process of splitting an atomic nucleus into two or more
nuclei with smaller masses (this occurs in nuclear ____________ plants)
IV. The Human Body—Balancing the Energy Equation
A) Energy ____________ in your body:
1) Your body stores energy in the form of ____________ and other chemical
compounds (this is chemical ____________ energy)
a) Used to fuel the processes that keep you alive:
 Making your ____________ beat
 ____________ your food, etc…
b) It is also converted to ____________ that is transferred to your
surroundings (used to make your body ____________)
B) __________ energy:
1) Food ____________ (C) is a unit used by nutritionists to measure how much
energy you get from various foods
a) 1 C = __________ Joules
b) Every gram of fat a person consumes can supply __________ Calories
of energy
c) ____________ and ____________ each supply about 4 Calories of
energy per gram.
d) Refer to Table 1 on page 143.
Section 5.1 Example problems
1. What is the kinetic energy of a baseball moving at a speed of 40 m/s if the baseball
has a mass of 0.15 kg?
KE = (1/2) (Mass) (Velocity)2
Ke =
M=
V=
2. A car moving at a speed of 20 m/s has a kinetic energy of 300,000 J. What is the car’s
mass?
KE = (1/2) (Mass) (Velocity)2
Ke =
M=
V=
3. A boulder has a mass of 80 kg and sits on the edge of a cliff that has a height of 1o m.
What is the Gravitational Potential Energy?
GPE = mass x gravity x height
GPE =
M=
G=
H=
4. Find the height of a baseball with a mass of 0.15 kg that has a GPE of 73.5 J.
GPE = mass x gravity x height
GPE =
M=
G=
H=
Section 2 Example Problems
5. What is the ME of a roller coaster on
the second hill if it has a PE of 50 J and
a KE of 100J ?
ME= PE + KE