Download Work at Work

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Section 4.1 Notes
Work
Work is the use of force to move an object
some distance.
Characteristics: requires exerting a force to
move something.
Example: writing a letter
Non-example: reading a letter
How do force and motion relate to work?
 Work requires both force
and motion.
 They are multiplied
together to find work.
 W= F x d
 Unit is Nm or Joule (J)
Calculating Work
 How would you
calculate the work of a
force of 18 N applied
over a distance of 5m?
 W = 18N x 5m
 W = 90J
Joule unit
 Unit is newton-meter (Nm)
 Fd
 Unit used to measure work
 1 J of work – 1 N of force used to move an object 1 m
Objects that are moving can do work.
 Objects can do work or work can be done on an object
 Objects in motion used throughout history do work
 Examples: water wheels-water turns a wheel that can be used to grind
grain, windmills- wind turns a wheel that can pump water
 In your notebook;
 Illustrate 3 examples of work and explain with a caption why it is work.
 Illustrate 1 example in which work is NOT being done and explain with a caption.
Complete the following work problems in your notebook.
Be ready to share on the whiteboard!
Chapter 4.1 – Work
Topic: Work is the use of force to move an object.
Vocabulary
Work
Joule
Procedure: Complete in your notebook.

Read section 4.1 (pages 112-119)

Answer questions 1-6 on page 119 in your science notebook

Finish Rollercoaster Webquest – due Friday

Finish Space Junk Solution Essay – due Tuesday

Begin the Chapter 4 Review Guide

Extension Activity - Energy Skate Park; Testing Static Electricity
Section 4.2 Notes - Energy
 Energy is the ability of an
object to do work or to cause
a change.
 Work can be thought of as
the transfer of energy.
 Both work and energy are
measured in joules.
 The total amount of energy
in a system never changes.
Can you think of an example of
when work transfers energy
from one form to another?
Potential Energy
 Stored Energy
 Gravitational potential




energy (GPE)
GPE = mgh
Mass x gravity x height
Gravity = 9.8m/s2
Can be converted into
kinetic energy
Kinetic Energy
 Energy of Motion
 KE = ½ mv2
 1/2 x (mass x velocity x
velocity)
 Can be converted to
potential energy
 Picture a rolling ball
Potential Energy & Kinetic Energy
Different Forms of Energy
Potential Energy
 Chemical energy is energy stored in the bonds of atoms and
molecules. Batteries, biomass, petroleum, natural gas, and coal are
examples of stored chemical energy. Chemical energy is converted
to thermal energy when we burn wood in a fireplace or burn
gasoline in a car's engine.
 Nuclear energy is energy stored in the nucleus of an atom – the
energy that holds the atom together.
 Gravitational energy is energy stored in an object's height. The
higher and heavier the object, the more gravitational energy is
stored. When you ride a bicycle down a steep hill and pick up
speed, the gravitational energy is being converted to motion
energy. Hydropower is another example of gravitational energy,
where the dam "piles" up water from a river into a reservoir.
Different Forms of Energy
Kinetic Energy
 Radiant energy is electromagnetic energy that travels in transverse waves. Radiant energy
includes visible light, x-rays, gamma rays and radio waves. Light is one type of radiant
energy. Sunshine is radiant energy, which provides the fuel and warmth that make life on
Earth possible.
 Thermal energy, or heat, is the vibration and movement of the atoms and molecules within
substances. As an object is heated up, its atoms and molecules move and collide faster.
Geothermal energy is the thermal energy in the Earth.
 Sound is the movement of energy through substances in longitudinal
(compression/rarefaction) waves. Sound is produced when a force causes an object or
substance to vibrate — the energy is transferred through the substance in a wave. Typically,
the energy in sound is far less than other forms of energy.
 Electrical energy is delivered by tiny charged particles called electrons, typically moving
through a wire. Lightning is an example of electrical energy in nature, so powerful that it is
not confined to a wire.
Mechanical energy is associated with the position or motion of an object. (ME = KE + PE)
Calculating GPE & KE & Mechanical Energy
 Gravitational potential energy = mass x gravitational acceleration x height
 GPE = mgh
 Unit: joules (J)
 Kinetic energy = ½ mass x velocity2

KE = ½
mv2
 Mechanical energy is the energy possessed by an object due to its motion
or position.
 Any object that has mechanical energy can do work on another object.
Mechanical energy = Potential energy + Kinetic Energy
ME = PE + KE
Conservation of Energy
 No matter how energy is transferred or transformed, the total
energy remains the same.
 If a skier at the top of a hill starts out with a total mechanical
energy of 200J, then at the middle of the hill they still have a
total mechanical energy of 200J. Total energy stays the same.
Challenge Question:
Is the Mechanical energy of the roller
coaster less at point A than it is at point
B? Why or why not? Ignore any losses to
friction in your answer.
A
B
Answer:
 It is the same at both points. Though the coaster’s potential and
kinetic energy may change in different places their sum is always
the same amount of mechanical energy.
When is mechanical energy not conserved?
 Friction converts some energy
into heat energy!
 Mechanical energy is not
conserved if energy is converted
to thermal energy (heat energy).
 The amount of mechanical
energy lost is converted to other
forms (PE, KE, Heat), so the
total energy is conserved.
Chapter 4.2 – Energy
Topic: Energy is transferred when work is done.
Vocabulary
Potential Energy
Kinetic Energy definition and Equation
Gravitational Potential Energy definition and Equation
Mechanical Energy definition and Equation
Law of Conservation of Energy
Procedure: Complete in your notebook.

Read section 4.2 (pages 121-128)

Answer questions 1-6 on page 128 in your science notebook

Finish Rollercoaster Webquest – due Friday

Finish Space Junk Solution Essay – due Tuesday

Begin the Chapter 4 Review Guide

Extension Activity - Energy Skate Park; Testing Static Electricity
Work at Work Poster
Design a poster depicting work! (15 AP)
Remember work requires a force being applied over
a distance… Work = Force x Distance
Poster Requirements:
• Title (Work at Work)
• Color illustration of work (force over a distance)
• Caption - explaining work (20-40 words)
1. Define work in society and physics
2. Explain how your example is work
3. Explain how it can be changed into a non-example.
• Name and Period written on the backside
Once done:
• Show the poster to Mr. Ganey for points
• Take the poster home and give it to your parents to take to
work…. (work at work poster) 
Chapter 4.3 Notes - Power
 Power-the rate at which you do work
 Power =Work/time
 Power = Energy/time
P=W/t
P= E/t
so, P=J/s
 Unit is the watt (W)
 J/s = 1 Watt; a 60 Watt light bulb uses 60J each second.
Horsepower
 James Watt was a Scottish inventor and
engineer who lived from 1736 to 1819 and
greatly improved steam engine performance.
 Watt used ponies to raise coal out of a mine
and needed a way to describe the rate at
which the pony worked.
 The term "horsepower" was coined by James
Watt to help market his improved 16
horsepower steam engine.
 Horsepower is based on the amount of work
a horse can do in a minute.
 1 horsepower = 745watts
 Wool and silk factories, and coal miners
began to join multiple steam engines together
to do work faster; to increase power.
Horsepower today:
 In modern times:
 Car engines are described
in horsepower.
 i.e. 250 horsepower engine
What is the difference between work
and power?
Power Activities
Directions: Activity One
Use the tweezers to move the macaroni, one at a time,
from one cup to the empty cup.
1. Make a prediction of how long it will take to move
the macaroni from one cup into the empty cup.
2. Record data for you and your partner.
Directions: Activity Two
Use the straw, by plugging one end of the straw with
your finger, to move water from one cup to the empty
cup.
1. Make a prediction of how long it will take to move
the water from one cup into the empty cup.
2. Record data for you and your partner.
Reflect: How are these activities examples of power?
(20-30 words)
Chapter 4.3 – Power
Topic: Power is the rate at which work is done.
Vocabulary
Power
Watt
Horsepower
Procedure: Complete in your notebook.

Read section 4.3 (pages 130-135)

Answer questions 1-6 on page 135 in your science notebook

Finish Rollercoaster Webquest – due Today

Complete the Chapter 4 Review Guide

Finish Space Junk Solution Essay – due Tuesday

Extension Activity: Work at Work Poster

Extension Activity - Energy Skate Park; Testing Static Electricity
Work at Work Poster
Design a poster depicting work! (15 AP)
Remember work requires a force being applied over
a distance… Work = Force x Distance
Poster Requirements:
• Title (Work at Work)
• Color illustration of work (force over a distance)
• Caption - explaining work (20-40 words)
1. Define work in society and physics
2. Explain how your example is work
3. Explain how it can be changed into a non-example.
• Name and Period written on the backside
Once done:
• Show the poster to Mr. Ganey for points
• Take the poster home and give it to your parents to take to
work…. (work at work poster) 
Chapter 4 Review
Agenda:
 Review Chapter 4
 pages 112-135
 Complete Chapter 4 Review
(Study Guide)
 Complete Work at Work Poster
 Extension Activity - Energy
Skate Park
Extension
 Energy Skate Park
 Learn about conservation of
energy with a skater dude!
Build tracks, ramps and jumps
for the skater and view the
kinetic energy, potential
energy, and friction as he
moves.You can also take the
skater to different planets or
even space!
 Testing Static Electricity
Extension
 Energy Skate Park
 Learn about conservation of
energy with a skater dude!
Build tracks, ramps and jumps
for the skater and view the
kinetic energy, potential
energy, and friction as he
moves. You can also take the
skater to different planets or
even space!
 Testing Static Electricity
How is electricity generated?
Generating Electrical Voltage
Energy Sources Video
Electricity is actually a secondary energy source, also referred
to as an energy carrier. That means that we get electricity from
the conversion of other sources of energy, such as coal, nuclear,
or solar energy. These are called primary sources. The energy
sources we use to make electricity can be renewable or nonrenewable, but electricity itself is neither renewable or
nonrenewable.
Power Plant Decision
The state of Arizona decides that a new
power plant is needed to reduce costs
and meet energy demands. You have
been appointed as an energy expert to
recommend a solution.
 What energy sources would
you have the state use?
 Write a 25-35 word
persuasive prompt explaining
why.
 Be prepared to debate your
decision with the class.