Download Kinetic Energy - Mat

RESOURCES
 Vocabulary Review: Quizlet Ch 15
 Doodle Science Playlist: High School Physics
The ability to do work
Work = Force x distance
Kinetic: energy of movement (depends on
mass and velocity)
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)
Energy is never created or destroyed – it is
transformed from one form to another.
(PE+KE)Beginning = (PE+KE)End
Often, kinetic energy will be transformed into
thermal energy, via FRICTION.
This is the reason we always LOSE efficiency
when work is done!
1 2
KE  mv
2
m = mass (kg)
v = velocity (m/s)
KE = kinetic energy (Joules)
What is the kinetic energy of a 75-kg student
running at a speed of 3 m/s?
1
2
KE  (75)(3)  338 J
2
A. Energy
THERMAL
The
ability
The ability
to to
cause change
cause
change.
internal motion of
particles
MECHANICAL
NUCLEAR
ENERGY
ENERGY
motion of objects
changes in the
nucleus
ELECTRICAL
CHEMICAL
bonding of atoms
joules (J)
motion of electric
charges
PE  mgh
m = mass (kg)
g = acceleration due to gravity (9.8 m/s2)
h = height (m)
PE = potential energy (Joules)
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
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!
Energy and Work
I.
Work & Energy
Conservation of Energy


A. Energy
THERMAL
The
ability
The ability
to to
cause change
cause
change.
internal motion of
particles
MECHANICAL
NUCLEAR
ENERGY
ENERGY
motion of objects
changes in the
nucleus
ELECTRICAL
CHEMICAL
bonding of atoms
joules (J)
motion of electric
charges
A. Energy
 Kinetic Energy (KE)
 energy in the form of motion
 depends on mass and velocity
• Which has the most KE?
80 km/h truck
• Which has the least KE?
50 km/h motorcycle
80 km/h
50 km/h
80 km/h
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?
B. Work
 Work
 transfer of energy through motion
 force exerted through a distance
W = Fd
W:
F:
d:
work (J)
force (N)
distance (m)
1 J = 1 N·m
Distance must be in direction of force!
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
W
F d
B. Work

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=?
W
F d
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.
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
C. Conservation of Energy
PE  KE
View pendulum animation.
View roller coaster animation.
C. Conservation of Energy
Mechanical  Thermal
View rolling ball animations.
View skier animation.
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.
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?
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
YOUR TURN TO DOODLE 
Writing/Drawing Assignment
 On a piece of paper draw & LABEL:
1. A building with a purpose of your choice

(i.e. gym/school/house, etc.)
Must use 4 types of Energy Resources
2.

Strive for a sustainable design.
Write a paragraph about your building:
3.




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?
HEAT – Thermal Energy Transfer
 Ch. 16.1 & 16.2 -- 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)
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 has a kinetic energy
of 14 J and a mass of 17 kg ,
how fast is the object moving?