Transcript I. Energy - School District of La Crosse

CHAPTERS 14&15
NOTES
KONICHEK
I. Energy is the ability to do work.
II Work is a transfer of energy.
Energy and Work
III. Work and energy are closely related.
A. Energy is known by the changes it causes.
B .Work is done when a force moves an object
through a distance.
1.Energy is transferred by a force moving an
object through a distance.
C. Both work and energy are typically measured
in joules (J).
Energy and Work
D.Energy has different forms.
A. The sun gives off energy in the form of heat and
light.
Energy and Work
A. The sun gives off energy in the form of heat and light.
1. Plants convert sunlight into food. -PHOTOSYNTHESIS
Energy and Work
Energy has different forms.
A. The sun gives off energy in the form of heat and
light.
B. Plants convert sunlight into food.
C. People convert food energy into muscle
movement.
V.The energy of motion is called
kinetic energy.
A.The kinetic energy of any
moving object depends upon its
mass and speed.
1 Doubling the mass in the
formula doubles the kinetic energy.

2.Doubling the speed
quadruples the kinetic energy.
VI. Potential Energy
A.Potential energy is energy that is stored as
a result of position or shape.
B.Gravitational Potential Energy
1. Potential energy that depends upon an
object’s height is called gravitational
potential energy
2.An object’s gravitational potential
energy depends on its mass, its height,
and the acceleration due to gravity.





C.The unit for height is meters.
1. Height is measured from the ground
or floor or some other reference level
D. Doubling either the mass of the object
or its height doubles its gravitational
potential energy.
E.Acceleration due to gravity, g, has a
value in SI units of 9.8 m/s2 on Earth.
F.The unit for gravitational potential
energy is joules.
G.Elastic Potential Energy
1.The potential energy of an object that
is stretched or compressed.
a.Something that is elastic springs
back to its original shape after it is
stretched or compressed.
VII. The major forms of energy are
mechanical energy, thermal energy,
chemical energy, electrical energy,
electromagnetic energy, and nuclear energy.
A.All energy can be considered to be one of three
forms:
• 1.kinetic energy,
• 2.potential energy, and
• 3.energy in fields such as those produced by
electromagnetic waves.
B. Conservation of Energy-Each of these forms
of energy can be converted into other forms of
energy.
C.Mechanical Energy
1.The energy associated with
the motion and position of
everyday objects is
2.Mechanical energy is the
sum of an object’s potential
energy and kinetic energy.
D.Thermal Energy
1.The total potential and kinetic energy
of all the microscopic particles in an
object.
2.When an object’s atoms move faster,
its thermal energy increases, and the
object becomes warmer.
E.Chemical Energy
1.Chemical energy is the energy stored
in chemical bonds.
A.When bonds are broken, the
released energy can do work.
1.All chemical compounds,
including fuels such as coal and gasoline,
store energy.
F.Electrical Energy
1.Electrical energy is the energy
associated with electric charges.
a.Electric charges can exert
forces that do work.
G. Electromagnetic EnergyOriginates from the electron
levels of the atom-quantum
physics
1.Electromagnetic energy is a
form of energy that travels through
space in the form of waves.
a. Visible light and X-rays are
examples of electromagnetic energy.
A. Lightning bolts transfer electric charge.
B. Galaxies are giant structures in space
that typically contain billions of stars. The
stars give off enormous amounts of
electromagnetic energy.
H. Nuclear Energy
1The nucleus of an atom is held together
by strong and weak nuclear forces, which
can store an enormous amount of potential
energy.
a. The energy stored in atomic nuclei is known
as nuclear energy.
b. Nuclear fission releases energy by splitting
nuclei apart.
c.Nuclear fusion releases energy when less
massive nuclei combine to form a more
massive nucleus.
OH NO A NASTY WORD
• I. WORK- THE MEASURE OF THE
EFFECTS OF A FORCE OVER A
DISTANCE
•
A. If the object doesn’t move , no
work is done
•
1. work= force x distance or
•
a.W=Fxd
•
1. units Nxm = JOULE
Work done pitching
POWER TO THE PEOPLE
• II. POWER- THE RATE WHICH WORK IS
BEING DONE
•
A. POWER= WORK / TIME,
•
1. P=W / T OR P= FXD / T
•
a. J/S= WATT
Hey, Hey, Hey
• III. MACHINES AND MECHANICAL
ADVANTAGE
• A. MACHINE- ANYTHING WHICH
MAKES WORK EASIER BY CHANGING
THE DIRECTION OR DISTANCE
THROUGH WHICH THE FORCE MOVES
•
1. MULITPLYING THE FORCE
HEY YA NEVER GET
SOMETHING FOR NOTHING!
 B. WORK INPUT EQUALS WORK
OUTPUT (WI=WO )

1. Fidi=Fodo

1. MAY USE LESS FORCE, BUT
HAVE TO MOVE IT A GREATER
DISTANCE.

a. GETTING UPSTAIRS.
WHO’S ADVANTAGE?
• C. MECHANICAL ADVANTAGE-TELLS
THE AMOUNT A MACHINE INCREASES
A FORCE.
•
1. A LONG RAMP PROVIDES A
GREATER M.A. THAN A SHORT RAMP
KONO IS BALD-HIS ADVANTAGE
D. TYPES OF MECHANICAL ADVANTAGE
1. IDEAL M.A.(IMA)= EFFORT
DISTANCE / RESISTANCE DISTANCE
a. IMA= ED/RD
1. DOESN’T DEAL WITH
FRICTION
2. ACTUAL M.A(AMA).=
RESISTANCE FORCE / EFFORT FORCE
a. AMA= RF/EF
1. DEALS WITH FRICTION
KONO’S MIND IS AN EFFICIENT
MACHINE
• E. Machine Efficiency- This is the ratio of
the work out to the work in
•
A .%E= {Work out/ work in}x100
•
1. %E= {Wo/Wi }x100
•
2. %E= (AMA/IMA)x100
•
B. Increasing Efficiency
•
1. lubrication, smoothing
It goes click cluck chug chug
• IV. SIMPLE MACHINE- any thing which
makes work easier by changing the
distance or direction of the force
•
A. THE 2 BASIC MACHINES ARE
LEVERS AND INCLINE PLANES.
•
1. All other machines are variations
of these 2
Whiz.fizz, boom, bang









VII SURVEY OF THE MACHINES
A. LEVER FAMILY- A LEVER IS A BAR OR BOARD FREE TO TURN
ABOUT A FIXED POINT.
1. FIXED POINT IS A FULCRUM
2. TYPE OF LEVER DEPENDS UPON WHERE THE FULCRUM IS
B. FIRST CLASS- THE FULCRUM IS BETWEEN THE RESISTANCE
FORE AND THE EFFORT FORCE –EXAMPLE-TEETER TOTTER.
C.SECOND CLASS- THE FULCRUM IS AT ONE END AND THE
RESISTANCE FORCE IS IN THE CENTER AND THE EFFORT FORCE IS AT
THE OTHER END- example-WHEEL BARROW.
D. THIRD CLASS LEVER- THE FULCRUM IS AT ONE END. THE
EFFORT FORCE IS IN THE CENTER AND THE RESISTANCE FORCE IS AT
THE OTHER END . EXAMPLE IS THE FOREARM
1. M.A FOR LEVERS:
A. IMA= EFFORT DISTANCE / RESISTANCE DISTANCE
1. IMA= ED/RD
3 classes of levers
You have to be pullying my leg





D. PULLEYS- A FIRST CLASS LEVER WHICH
ROTATES ABOUT THE FULCRUM
1. SINGLE FIXED PULLEY-CHANGES THE
DIRECTION OF THE FORCE- PULLEY---M.A. IS 1FORCE IN GETS AN EQUAL FORCE OUT.
2. BLOCK AND TACKLE- MULTIPLE PULLEY
SYSTEMS.
a. CHANGES THE DIRECTION OF THE
FORCE AND PROVIDES A M.A
3. THE M.A. IS EQUAL TO THE NUMBER OF
SUPPORT ROPES OF THE SYSTEM.
Single fixed pulley
Movable pulley
Hey I’m a big wheel, but some
people think I’m an axle
• E. WHEEL AND AXLE-A WHEEL OR PULLEY
CONNECTED TO A SHAFT.
•
1. STEERING WHEEL OF A CAR
•
a. door knob
•
2. M.A= WHEEL RADIUS / AXLE
RADIUS
•
a. IMA= WR/AR
•
3. To increase M.A. The wheel radius
must be made larger
Wheel and axle
Very nice family
• 2. INCLINE PLANE FAMILY
•
A. INCLINE PLANE(RAMP) A SLANTED SURFACE USED
TO RAISE AN OBJECT.
•
1. BY INCREASING THE LENGTH OF THE INCLINE
THE M.A. INCREASES
•
a. turns a small effort force into a large output force.
•
2. IMA= LENGTH / HEIGHT.
•
B. WEDGE- TWO INCLINE PLANES PUT BACK TO BACKTHE WEDGE DOES THE MOVING THROUGH THE SUBSTANCENAIL, KNIFE, WOOD WEDGE.
•
C. SCREW- AN INCLINE PLANE WRAPPED AROUND AN
CYCLINDER.
•
1. THE MORE THREADS ON THE SCREW THE
GREATER THE M.A.
Incline plane
WEDGE
Want to play with my wedge?
SCREWING AROUND?
Screw moves through a substance
• VI COMPOUND MACHINE-A MACHINE
MADE UP OF ONE OR MORE SIMPLE
MACHINES
•
A. bicycle- levers pulleys, wheel and
axle
Can you name the simple
machines that make up this
compound machine