Lesson Plan on Energy Unit merged

Lesson Plan on Energy Unit

Holl ie O’Brien

MIT Fal l 2013

11.129 Final Portfol io Project

Energy Unit Day 1

Concepts 1. Energy is the ability to do work and is used in order to perform work.

2. Power is the rate at which work is done.

3. There are mathematical representations of work and power.

4. There are various units of energy, work, and power.

Key Questions 1. How do you describe the relationship between energy, work, and power?

2. How do you represent the relationships between the three, using mathematical formulas?

Learning Objectives: Students will able to define and contrast energy, work, and power.

Given mass, distance, and time, the student will be able to calculate work and power using appropriate

units.

Alignment of learning objectives with Massachusetts State Framework:

Conservation of Energy and Momentum

Broad Concept: The laws of conservation of energy and momentum provide alternate approaches to predict and describe the movement of objects.

2.1 Interpret and provide examples that illustrate the law of conservation of energy. *

2.2 Provide examples of how energy can be transformed from kinetic to potential and vice versa.

2.3 Apply quantitatively the law of conservation of mechanical energy to simple systems.

2.4 Describe the relationship among energy, work, and power both

conceptually and quantitatively.

2.6 Identify appropriate standard international units of

measurement for energy, work, power, and momentum.

Detailed Lesson Plans:

Do Now:

Introduce energy with word association brainstorm –What do students think about when they hear the term “Energy?”

Where/how do you use energy in your lives? Name a few things that we do that use

energy.

What happens when we don’t have access to energy (electric power)(e.g. summer

blackout/ice storms)?

Lead to concepts of energy in a useful form to provide heat, power or do work for human use.

Note – everything is either capable of providing energy or has energy, until there is none left – has been transformed to something else

Hand out vocabulary sheet –indicate that students should fill in as go. Have copy on the board –fill in definitions and equations in appropriate places as proceed.

Watch Eureka! Video at

http://www.youtube.com/watch?v=xBnS23U_ao4&list=PLT8RCCgU0GtmKuCDkx2MMk2x7UwJrPoD5

Write Definitions on the board (or you could just give them the sheet already filled in)

A force is a push, pull, or twist

Force = mass X acceleration Drop a ball . What is pulling it towards the ground? Gravity. (Acceleration of gravity (9.81 m/s 2). ) Energy is the ability to do work

Work is a force acting over a distance to move an object

Work = force X distance

Power is how fast work is done (or the rate at which work is done)

Power=work/time OR Power=energy used/time

Re-enforce the concept of work with the Student Push/Pull Demo

Ask for two volunteers.



Have one push against the wall and one push on a chair so that the chair moves at least 0.5 meters.

Discuss as a class o Did either one or both of these students do any work? The one pushing on the chair did

work; the other did not. “Work” requires that an object be moved. o Did either of these expend energy? Yes – energy contributes to doing work, but not all

energy successfully does work Go over SI Units (System Internationale)

We use this so that parts made in the US and in other parts of the world match (an engine built in

Japan can fit in a car made in the US since the measurements are the same)

Mass kilogram (kg)

Distance meters (m)

Time second (s)

Velocity meters per second (m/s)

Acceleration meters per second squared (m/s2)

Energy Joule (J)

Force Newton (N)

o A Newton is also a kg*m/s2 o We determine this by plugging the units into the equation o Force=mass*acceleration

Work Joule (J) ƒ o A Joule is also a N*m (work = force x distance)

Power Watt (W) o A Watt is also a J/s or N*m/s

o An easy way to remember the Watt is to ask the k ids “Watt (What) is the unit of Power?” They like that.

There are two units that we will use to measure energy 1. British Thermal Unit (BTU): There are 1055 Joules in one BTU. This unit is used when we

measure large amounts of energy. For example we would measure the amount of energy is the

USA’s oil reserves in BTU. 2. Kilowatt Hour (kWh): This is how the electrical energy you use in your home is measured on your

electricity bill. It is how many kilowatts you use in an hour.

a. 1000 W = kW b. energy = power (kW)* time (h)

Extension – besides electrical energy, what other type of energy does our home consume a lot of in the north? HEAT! does anyone know the energy term used to measure the amount of natural gas we use to heat our homes?

Therm. 1 therm = 100,000 BTU.

Closure: Assign homework

Ask – what did we learn today? Can anyone define work, power, energy?

Homework:

Read Chapter 8 pages 103-105 in textbook

Complete the Work and Power sections in the Student Packet

Labs/Demos/Web Resources: See all the resources

Assessment Components: Students will be working on the packet to assess learning

Energy Unit Day 2







Learning Objectives: Given mass, distance, and time, the student will be able to calculate work and power using

appropriate units.

Given the conversion formulas, the student will be able to calculate horsepower and kilowatt equivalence.

Students will use measurement tools to apply the concepts of work, power, and energy to a real life example

Alignment of learning objectives with State Framework:

Mass Conservation of Energy and Momentum





2.4 Describe the relationship among energy, work, and power both conceptually and quantitatively.

2.6 Identify appropriate standard international units of measurement for energy, work,

power, and momentum.

Detailed Lesson Plans: Have student demonstrate human power experiment – (no measurement)

Discuss what happened – use discussion to review energy, work, and power– go over equations and units for force, work, power.

o Work = force x distance Where Force = mass x acceleration

o Power = work/time

Ask students – if we wanted to determine how much work student just did, what could we measure? (mass, time, distance – can’t measure force directly in this case)

Introduce Human Power Activity. This activity will require students to collect data for mass, distance and time. The activity sheet lists equipment needed, but you may want to substitute heavier bottles so the students can “feel” the work they do (2-liter or gallon milk jugs work well).

Using the data collected in the Activity, calculate average time and apply the appropriate formulas to calculate work and power. Calculate a few of the trials in class, have students finish the calculations for homework.

Hold up a 60 Watt light bulb and ask if anybody in the class produced enough power to light the

bulb (hopefully no one actually does). Ask if they could produce more power possibly with their legs. (Give the example of the human powered bike headlights).

Ask and/or lead a student (on the board) through a calculation of how many of themselves it

would take to light the bulb, based on their power output from the activity. # of people to light

60 Watt bulb = 60 watts/power from the activity. (For example, if the student’s name was Nate and it took 300 of them to light the bulb, it is therefore a 300 natepower bulb.)

If time allows, convert watts to horsepower in activity

Homework:

Read page 104-111

Finish Power part of packet

Labs/Demos/Web Resources: See Resources

Assessment Components: Students will complete the homework.

Energy Unit Day 3







Learning Objectives: Given mass, distance, and time, the student will be able to calculate work and power using appropriate units.

Given the conversion formulas, the student will be able to calculate horsepower and kilowatt

equivalence.

Students will use measurement tools to apply the concepts of work, power, and energy to a real life example

Alignment of learning objectives with with State Framework:







2.6 Identify appropriate standard international units of measurement for energy, work, power, and momentum.

Detailed Lesson Plans: You will probably need to use the beginning of this class to wrap up the Human Power Activity.

Start the rollercoaster lab online. It will take the whole period.

Homework:

Finish the packet

Labs/Demos/Web Resources: See resources.

Assessment Components: Students will be assessed using the packet.

Energy Unit Day 4







Learning Objectives: Students will interpret examples that illustrate the law of conservation of energy.

Students will identify how energy can be transformed from kinetic to potential and vice versa.








2.6 Identify appropriate standard international units of measurement for energy, work,

power, and momentum.

Detailed Lesson Plans: Finish the online rollercoaster lab.

Go over the whole homework packet and check in class.

The students can ask questions since the quiz is on day 5.

Homework:

Study for Quiz

Labs/Demos/Web Resources: See resources

Assessment Components: Students will be quizzed.

Energy Unit Day 5







Learning Objectives: Students will describe the relationship among energy, work, and power both conceptually and

quantitatively.








2.6 Identify appropriate standard international units of measurement for energy, work, power, and momentum.

Detailed Lesson Plans: Answer any last minute questions to prep for the quiz.

Allow at least half the period for the students to complete the Energy Basics Assessment

Have students read pg. 111-118 to prepare to cover mechanical machines.

Labs/Demos/Web Resources: See resources.

Assessment Components: Students are quizzed.

Definition and Formulae

Key Terms

Force A force is a push, pull, or twist

=mass x acceleration Newton (N) =kg/m/s2

Joule the SI unit for energy and work.

J = W·s = N·m

Energy

the ability to do work

=power x time

Joule

Work

Work is a force acting over a distance to move an object

= force x distance

Joule (J)

Power The rate at which work is done

= work / time (or =energy/time)

Watt = J/s

Meter

the SI (Standard International) unit for distance

m

Kilogram

the SI unit for mass

kg

Btu

The amount of energy needed to raise 1 lb of water 1 degree Fahrenheit (1 Btu ~ heat energy from one wooden match)

1 Btu = 1055 Joules

Kilowatt

Typical unit for electrical power

1 kW = 1000 watts

Horse power

Unit for mechanical or electrical power

1 hp = 746 watts

Kilowatt hour

Typical unit for electrical energy

kWh

Definition and Formulae

Force:

Energy:

Work:

Power:

Meter:

Kilogram:

Newton:

Joule:

Btu:

Watt:

Kilowatt:

Energy Basics Assessment

Name: ________________________

You have 20 minutes to complete all of the questions. Questions 1-4 all correspond to the diagram below.

Questions 5-9 are separate and must be answered within the allotted time.

1. Write the equation for WORK.

2. If it takes 5 newtons of force to move the wagon 5 meters, how much work is being done? Remember to

use the correct units.

3. What are the units for POWER?

4. If it took 10 seconds to move the wagon, how much

power was provided?

5. What is the definition of ENERGY?

6. What S.I. unit do we use for MASS?

7. A BTU is used to describe what type of measurement?

8. FORCE is measured using (please circle the correct

answer) a. Newtons

b. Joules

c. Kilograms

9. List three choices you can make to reduce the amount of energy you use in your life.

10. Explain why it is important to think about how much energy you use in your life.

Energy Basics Assessment Name: ________________________ You have 20 minutes to complete all of the questions.

Questions 1-4 all correspond to the diagram below. Questions 5-9 are separate and must be answered within the

allotted time.

11. Write the equation for WORK.

Work = Force x distance

12. If it takes 5 newtons of force to move the wagon 5 meters, how much work is being done? Remember to

use the correct units.

Work = 5 newtons x 5 meters = 25 joules

13. What are the units for POWER?

Watts, Kilowatts

14. If it took 10 seconds to move the wagon, how much

power was provided?

Power = Work/time = 25 joules/10 seconds = 2.5 Watts

15. What is the definition of ENERGY?

The ability to do work

16. What S.I. unit do we use for MASS?

Kilograms

17. A BTU is used to describe what type of

measurement?

Another form of Energy Units –British Thermal Units

18. FORCE is measured using (please circle the correct

answer) a. Newtons

b. Joules c. Kilograms

19. List three choices you can make to reduce the

amount of energy you use in your life.

Turn of lights, buy energy efficient appliances, buy CFLs instead of incandescent, etc…

20. Explain why it is important to think about how much energy you use in your life.

The depletion of oil, environmental, societal, and economical

impacts.

Activity: Human Power

Purpose Work and power are important concepts that deal with energy. Work is a force over a

given distance and power is the amount of work done in an amount of time. The goal of this experiment is to get familiar with these concepts.

Equipment

1.Scale 2.Stopwatch 3.large bottle filled with water 4.meter stick 5.pole 6.rope

Procedure Set up the experiment:

1. Split into groups of 3-4 students.

2. Collect all equipment and materials necessary to conduct the activity.

3. Attach one end of the rope to the bottle and the other end to the middle of the

pole. 4. Measure the distance of the rope from the pole to the bottle and record it on the

space given (meters, m). Do work and collect data 5. Have each person stand on a chair and hold the pole horizontally so that the

bottle is suspended. Twist the pole so the rope winds around it, lifting the bottle.

Time how fast each person can wind the rope to bring the bottle all the way up to the pole. Record your data (in seconds).

6. Repeat so that each student has 3 tries, and record each time. 7. Using the given mass for your bottle, calculate Force by using:

a. Force (N) = mass (kg) x acceleration (m/ s2 )

b. Mass, m = given (kg) c. Acceleration due to gravity, a = 9.81 m/ s2

8. Record the force on the worksheet. 9. Use the worksheet to calculate average time for each person, work, power in

Watts and horsepower (remember that 1 hp = 746 watts).

Discussion Questions:

1. What is power?

2. What does it mean if one person has a higher value for power?

3. How many of you would it take to light a 60 Watt light bulb?

a. 60 Watts ÷ Your Power (from the table) = _________ “your name”power b. 60 Watts ÷ ________Watts = _________ “________ “ power

4. How does your person power compare to the horsepower in a car? (Use an estimated horsepower of 166)?

Name: _________________________ Date: ___________

Online Simulation Lab ROLLER COASTER PHYSICS

Purpose: The purpose of this simulation lab is to strengthen your understanding

of energy conservation in real-world applications. You will use a skateboarder and

his park to represent the roller coaster and its track. You will observe many other

physics concepts at work as well.

Pre-Lab Inquiry

What Do You Think?

You are asked to design a new roller coaster. It is totally up to you to determine

what the riders will experience. The only rule is that the coaster obeys the laws of

physics. Take a minute and brainstorm about a design you would like.

1. Name three adjectives that will describe your roller coaster.

2. Describe three features your roller coaster will have that will attract riders.

3. Name three variables that will affect the type of experience a rider will have. EXPLAIN.

4. Name three concepts of physics that the roller coaster must obey in order to be successful. EXPLAIN.

5. Draw a side-view sketch of your roller coaster design below.

Concept Review

Write out an explanation for each question below.

6. Define potential and kinetic energy.

7. Describe when potential and kinetic energy are at their highest on a roller

coaster.

8. How does conservation of energy apply to roller coasters?

9. How does friction affect a roller coaster?

10.What is responsible for the apparent change in weight that riders experience on coasters?

Internet Lab Activity

Open up the University of Colorado, PhET Energy Skate Park simulation:

1. Go to http://phet.colorado.edu/ 2. Click “Play with Sims…>” 3. Click the “Energy Skate Park” icon 4. Click “Run Now!” 5. Spend ONE MINUTE to explore the simulation and familiarize yourself with

the controls. 6. Click the “Reset” button in the top-right corner. Begin the exploration

below.

Exploration Questions

Use the simulation to answer the questions below.

1. Does the skater hit the same height on the opposite sides of the track? (Checkmark the “Show Grid” button to help you determine this!)

a. What must be true about the system for this to be possible?

b. Click the “Track Friction >>” button to adjust the friction settings. What do you observe about the skater as you adjust the setting?

2. Now, turn on the energy Pie Chart and Bar Graph. (You may need to move things around a little to see everything.)

a. On the visual aids, what color represents potential energy and which is kinetic energy?

http://phet.colorado.edu/

b. When does the skater have the highest amount of kinetic energy? Potential energy?

c. When does the skater have the lowest amount of kinetic energy? Potential energy?

d. Describe how the bar graph changes as the skater moves along the track.

e. Explain which visual aid (pie chart or bar graph) helps you understand conservation of energy better, and why.

f. Keep your preferred visual aid open for the remainder of the investigation.

Build Your Roller Coaster

Use the simulation to build and test your roller coaster design from the Pre-Lab

Inquiry.

1. If you made any changes during the Exploration Questions, click “Reset” again.

2. Right-click the track and select “Roller Coaster Mode”. This keeps the skater attached.

3. Notice that you can zoom out to give yourself a wider view. You may want to do this as you build your coaster.

4. Drag in new pieces of track and manipulate the curves until you closely match your pre-lab sketch.

5. Drag and drop the rider to the location of the beginning and observe. DO NOT MAKE CHANGES YET.

a. The ride probably was not successful on the first attempt. If not, what physics concept(s) was violated?

b. Identify several adjustments you need to make.

6. After making the initial adjustments, try the ride again. Continue making adjustments until the ride becomes successful (rider makes it from one end to the other completely – does not have to make it back through).

7. Raise your hand and show the teacher your successful design. 8. Draw a side-view sketch of your successful design below.

9. Label the points of acceleration on your sketch. a. Down arrow = slowing down b. Up arrow = speeding up c. Circle arrow = changing direction

10.Click the “Track Friction >>” button and adjust the setting. 11.Run the rider through your track again and observe the changes.

a. Did the rider make it to the end?

b. What do you notice differently about the pie chart and/or bar graph?

12.Describe the changes you need to make to your design, as a result of the presence of friction.

13.Make the necessary adjustments until you achieve a successful ride with friction.

14.Raise your hand and show the teacher your friction-savvy coaster. 15.Draw a side-view sketch of your friction-savvy coaster below.

Post-Lab Questions:

1. List and explain the differences between each of your sketches.

2. At the top of a hill on the ride, most of the energy is _______________ and at the bottom of the hill, most of the energy is converted into _________________.

3. What are the equations for potential and kinetic energy?

4. If you were an engineer of an actual roller coaster, what information would you need to know in order to ensure that your coaster would be safe?

5. Would it be possible to predict the speeds that a coaster will reach before it’s ever placed on the track? How?

6. The most thrilling roller coasters usually contain vertical loops. What keeps the riders in their seats when they go upside-down?

7. Consider going around a horizontal turn to the right. If the coaster suddenly slipped off the track, what path would it follow? Draw a top-view sketch below.

8. You should have drawn the coaster following a straight line after it slipped off the track. Since that is the path it would take without the track, there must be an unbalanced force causing it to accelerate (turn) around the bend. What direction is that force pointing? Draw a top-view sketch of the force vectors below.

Name: _____KEY____________________ Date: ___________

Online Simulation Lab ROLLER COASTER PHYSICS

Purpose: The purpose of this simulation lab is to strengthen your understanding

of energy conservation in real-world applications. You will use a skateboarder and

his park to represent the roller coaster and its track. You will observe many other

physics concepts at work as well.

Pre-Lab Inquiry

What Do You Think?

You are asked to design a new roller coaster. It is totally up to you to determine

what the riders will experience. The only rule is that the coaster obeys the laws of

physics. Take a minute and brainstorm about a design you would like.

11.Name three adjectives that will describe your roller coaster.

ANSWERS WILL VARY WITH STUDENT

12.Describe three features your roller coaster will have that will attract riders.


13.Name three variables that will affect the type of experience a rider will have. EXPLAIN.


Possible answers include: height (affects max potential energy), speed/

velocity(force rider experiences), angle of incline of track, and ect. There

could be a variety of answers so make sure students explain.

14.Name three concepts of physics that the roller coaster must obey in order to be successful. EXPLAIN. Conservation of momentum, conservation of energy, Newton’s third law,

etc (as long as the student explains).

15.Draw a side-view sketch of your roller coaster design below.


Concept Review

Write out an explanation for each question below.

16. Define potential and kinetic energy.

Potential—the energy that is possible due to position

Kinetic—the energy of motion

17. Describe when potential and kinetic energy are at their highest on a roller coaster.

Potential—top of the tallest hill

Kinetic—deals with motion. Max kinetic is when potential is lowest at the

bottom of a giant hill

18.How does conservation of energy apply to roller coasters?

As a rollercoaster goes down the hill, the potential energy turns into kinetic (no

energy is lost). As height decreases, speed increases.

19.How does friction affect a roller coaster?

Friction slows down a rollercoaster.

20.What is responsible for the apparent change in weight that riders experience on coasters?

The acceleration of a rider makes them feel lighter/heavier depending on if

they are counteracting gravity (going up a hill) or adding on to it (by dropping

down).

Internet Lab Activity

Open up the University of Colorado, PhET Energy Skate Park simulation:

7. Go to http://phet.colorado.edu/en/simulation/energy-skate-park-basics 8. Click “Run Now!” 9. Spend ONE MINUTE to explore the simulation and familiarize yourself with

the controls. 10.Click the “Reset” button in the top-right corner. Begin the exploration

below.

Exploration Questions

Use the simulation to answer the questions below.

3. Does the skater hit the same height on the opposite sides of the track? (Checkmark the “Show Grid” button to help you determine this!)

yes

a. What must be true about the system for this to be possible? It is frictionless

b. Click the “Track Friction >>” button to adjust the friction settings. What do you observe about the skater as you adjust the setting?

The more the friction, the sooner the rider comes to a stop.

4. Now, turn on the energy Pie Chart and Bar Graph. (You may need to move things around a little to see everything.)

a. On the visual aids, what color represents potential energy and which is kinetic energy?

Green—kinetic

Blue--potential

b. When does the skater have the highest amount of kinetic energy? Potential energy?

Max kinetic at bottom of parabola. Max potential at tops of parabola.

http://phet.colorado.edu/en/simulation/energy-skate-park-basics

c. When does the skater have the lowest amount of kinetic energy? Potential energy?

Min kinetic at tops of parabola. Min potential at bottom of parabola.

d. Describe how the bar graph changes as the skater moves along the track.

The bars switch from kinetic to potential exactly.

e. Explain which visual aid (pie chart or bar graph) helps you understand conservation of energy better, and why.


f. Keep your preferred visual aid open for the remainder of the investigation.

Build Your Roller Coaster

Use the simulation to build and test your roller coaster design from the Pre-Lab

Inquiry.

16.If you made any changes during the Exploration Questions, click “Reset” again.

17.Right-click the track and select “Roller Coaster Mode”. This keeps the skater attached.

18.Notice that you can zoom out to give yourself a wider view. You may want to do this as you build your coaster.

19.Drag in new pieces of track and manipulate the curves until you closely match your pre-lab sketch.

20.Drag and drop the rider to the location of the beginning and observe. DO NOT MAKE CHANGES YET.

a. The ride probably was not successful on the first attempt. If not, what physics concept(s) was violated?


b. Identify several adjustments you need to make.


21.After making the initial adjustments, try the ride again. Continue making adjustments until the ride becomes successful (rider makes it from one end to the other completely – does not have to make it back through).

22.Raise your hand and show the teacher your successful design. 23.Draw a side-view sketch of your successful design below.


24.Label the points of acceleration on your sketch. a. Down arrow = slowing down b. Up arrow = speeding up c. Circle arrow = changing direction

25.Click the “Track Friction >>” button and adjust the setting. 26.Run the rider through your track again and observe the changes.

a. Did the rider make it to the end? (most likely no)


b. What do you notice differently about the pie chart and/or bar graph? More and more energy went to thermal

27.Describe the changes you need to make to your design, as a result of the presence of friction.

ANSWERS WILL VARY WITH STUDENT (making the starting height higher or

lowering a loop-the-loop are two examples.)

28.Make the necessary adjustments until you achieve a successful ride with friction.

29.Raise your hand and show the teacher your friction-savvy coaster.

30.Draw a side-view sketch of your friction-savvy coaster below.


Post-Lab Questions:

9. List and explain the differences between each of your sketches.


10.At the top of a hill on the ride, most of the energy is ___potential_________ and at the bottom of the hill, most of the energy is converted into ____kinetic_____________.

11.What are the equations for potential and kinetic energy?

Kinetic energy: KE= 1

2 mv2

Potential Energy: PE=mgh

12.If you were an engineer of an actual roller coaster, what information would you need to know in order to ensure that your coaster would be safe?


Examples include: speed, the force “g” that a rider will feel, strength of metal or

whatever materials it is built out of, and etc.

13.Would it be possible to predict the speeds that a coaster will reach before it’s ever placed on the track? How?

Yes, you can estimate by using the conservation of energy. As potential energy

switches to kinetic, you can solve for the velocity.

14.The most thrilling roller coasters usually contain vertical loops. What keeps the riders in their seats when they go upside-down?

Centripetal force—the component of the

momentum that is changing. **this is an important concept

15.Consider going around a horizontal turn to the right. If the coaster suddenly slipped off the track, what path would it follow? Draw a top-view sketch below.

straight line after it slipped off the track

16.You should have drawn the coaster following a straight line after it slipped off the track. Since that is the path it would take without the track, there must be an unbalanced force causing it to accelerate (turn) around the bend. What direction is that force pointing? Draw a top-view sketch of the force vectors below.

pointing perpendicular to the turn

D irections:

W o rk through this p acket of fi ll in the blank definitions, multiple choice questions,

a n d calculation p roblems. Show y our work whenever d oing a calculation. Show u nits

o n e very single s tep.

Work (CH 8 pg 103-104)

Definitions: (fill in the blank)

An impulse is a force acting over some amount of time to cause a change in

momentum. On the other hand, work is a ______________ acting over some

amount of ___________________ to cause a change in __________________.

Examples of work:

1. Indicate whether or not the following represent examples of work.

a. A teacher applies a force to a wall and becomes exhausted. Work done? Yes or No?

Explanation:_________________________________________

________________________________________________________________________________________________________________

________________________________________________________ b. A weightlifter lifts a barbell above her head.

Work done? Yes or No?

Explanation:_________________________________________________________________________________________________

________________________________________________________________________________________________________________

c. A waiter carries a tray full of meals across a dining room at a constant speed.


Explanation:_________________________________________________________________________________________________________________________________________________________

_______________________________________________

d. A rolling marble hits a note card and moves it across a table.


Explanation:_________________________________________________________________________________________________

________________________________________________________

________________________________________________________

e. A shot-putter launches the shot. Work done? Yes or No?

Explanation:_________________________________________

________________________________________________________________________________________________________________

________________________________________________________

2. Work is a ______________; a + or - sign on a work value indicates information about _______.

a. vector; the direction of the work vector b. scalar; the direction of the work vector

c. vector; whether the work adds or removes energy from the object d. scalar; whether the work adds or removes energy from the object

3. Which sets of units represent legitimate units for the quantity work? Circle all correct answers.

a. Joule b. N * m

c. Foot * pound d. kg * m/sec

e. kg * m/sec2 f. kg * m2/sec2

Helpful Hint!

The amount of work (W) done on an object by a given force can be calculated using the formula:

W = F*d*cosΘ Where F is the force and d is the distance over which the force acts and Θ is the

angle between F and d. It is important to recognize that the angle included in the equation is not just any old angle; it has a distinct definition that must be

remembered when solving such work problems.

Calculate!

4. For each situation below, calculate the amount of work done by the applied force.

5. Before beginning its initial descent, a roller coaster car is always pulled up the first hill to a high initial height. Work is done on the car (usually by a

chain) to achieve this initial height. A coaster designer is considering three different angles at which to drag the 2000-kg car train to the top of the 60-meter high hill. Her big question is: which angle would require the most

work?___________________ Show your answers and explain!!!

Angle Force Distance Work

35° 1.15 * 104 N 105 m

45° 1.41 * 104 N 84.9 m

55° 1.64 * 104 N 73.2 m

6. The following descriptions and their accompanying free-body diagrams

show the forces acting upon an object. For each case, calculate the work done by these forces; use the format of force • displacement • cosine(Θ). Finally, calculate the total work done by all forces.

7. When a force is applied to do work on an object, does the object always

accelerate? __________ a. Explain why or why not.

8. Determine the work done in the following situations.

a. Jim Neysweeper is applying a 21.6-N force downward at an angle of 57.2° with the horizontal to displace a broom a distance of 6.28 m.

b. Ben Pumpiniron applies an upward force to lift a 129-kg barbell to a height of 1.98 m at a constant speed.

c. An elevator lifts 12 occupants up 21 floors (76.8 meters) at a constant

speed. The average mass of the occupants is 62.8 kg.

Power (CH 8 pg 104-105)

Review:

1. A force acting upon an object to cause a displacement is known as _____.

a. Energy b. Potential

c. Kinetic d. Work

2. Two acceptable units for work are ________. Choose two. a. Joule b. Newton

c. Watt d. Newton•meter

Power as a Rate Quantity:

3. Power is defined as the _______ is done.

a. amount of work which b. direction at which work c. angle at which work

d. the rate at which work 4. Two machines (e.g., elevators) might do identical jobs (e.g., lift 10

passengers three floors) and yet the machines might have different power outputs. Explain how this can be so.

5. There are a variety of units for power. Which of the following would be fitting units of power (though perhaps not standard)? Include all that apply.

a. Watt b. Joule

c. Joule / second d. Hp

6. Two physics students, Will N. Andable and Ben Pumpiniron, are in the weightlifting room. Will lifts the 100-pound barbell over his head 10 times

in one minute; Ben lifts the 100-pound barbell over his head 10 times in 10 seconds. Which student does the most work? ______________

Which student delivers the most power? ______________ Explain your answers.

7. An often-used equation for power is Power = force*velocity Express an

understanding of the meaning of this equation by using it to explain what type of individuals would be the best choice for lineman on a football team.

Energy (CH 8 pg 105-111)

Definitions:

1. Potential energy is the ________________ energy of position possessed

by an object. 2. Kinetic energy is the energy of _________________.

3. The total amount of mechanical energy is merely the sum of the -

___________ energy and the _________________ energy. This sum is simply referred to as the total mechanical energy (abbreviated TME).

Calculate!

4. Read each of the following statements and identify them as having to do

with kinetic energy (KE), potential energy (PE) or both (B).

KE, PE or B? Statement:

a) If an object is at rest, it certainly does NOT possess this form of

energy. b) Depends upon object mass and

object height.

c) The energy an object possesses due to its motion.

d) The amount is expressed using the

unit joule (abbreviated J).

e) The energy stored in an object due

to its position (or height).

f) The amount depends upon the arbitrarily assigned zero level.

g) Depends upon object mass and

object speed.

h) If an object is at rest on the ground

(zero height), it certainly does NOT possess this form of energy.

5. A toy car is moving along with 0.40 joules of kinetic energy. If its speed

is doubled, then its new kinetic energy will be _______. a. 0.10 J

b. 0.20 J c. 0.80 J

d. 1.60 J e. still 0.40 J

6. A young boy's glider is soaring through the air, possessing 0.80 joules of

potential energy. If its speed is doubled and its height is doubled, then the new potential energy will be _______.

a. 0.20 J b. 0.40 J

c. 1.60 J d. 3.20 J

e. still 0.80 7. Which would ALWAYS be true of an object possessing a kinetic energy

of 0 joules? a. It is on the ground.

b. It is at rest. c. It is moving on the ground

d. It is moving. e. It is accelerating.

f. It is at rest above ground level g. It is above the ground.

h. It is moving above ground level. 8. Which would ALWAYS be true of an object possessing a potential

energy of 0 joules? a. It is on the ground.




h. It is moving above ground level. 9. Calculate the kinetic energy of a 5.2 kg object moving at 2.4 m/s.

10. Calculate the potential energy of a 5.2 kg object positioned 5.8 m above

the ground.

11. Calculate the speed of a 5.2 kg object that possesses 26.1 J of kinetic

energy.

D irections:

W o rk through this p acket of fi ll in the blank definitions, multiple choice questions,

a n d calculation p roblems. Show y our work whenever d oing a calculation. Show u nits

o n e very single s tep.

Work (CH 8 pg 103-104)

Definitions: (fill in the blank)

An impulse is a force acting over some amount of time to cause a change in

momentum. On the other hand, work is a __object____________ acting over some

amount of ________distance___________ to cause a change in

__force________________.

Examples of work:

9. Indicate whether or not the following represent examples of work.

a. A teacher applies a force to a wall and becomes exhausted. Work done? Yes or No?

Explanation:____ This is not an example of work. The wall is

not displaced. A force must cause a displacement in order for work to

be done. ________________________________________________________

______ b. A weightlifter lifts a barbell above her head.


Explanation:_______change in height means gravity acted against the displacement thus there is an increase in potential energy_

________________________________________________________

____________________________________________________________________

c. A waiter carries a tray full of meals across a dining room at a constant speed.


Explanation:____ This is not an example of work. There is a force (the waiter pushes up on the tray) and

there is a displacement (the tray is moved horizontally across the room). Yet the force does not cause the displacement. To

cause a displacement, there must be a component of force in the direction of the displacement.

d. A rolling marble hits a note card and moves it across a table. Work done? Yes or No?

Explanation:_______ This is an example of work. There is a force (the marble pushing the card) which causes the card to be

displaced across the table. _______________________ e. A shot-putter launches the shot.


Explanation:___ This is an example of work. There is a force (the hand pushing the shot put) which causes the

shot put to be displaced upwards before the person lets go. Once they let go, they are not doing work

anymore.______________________________________ 10. Work is a ______________; a + or - sign on a work value

indicates information about _______.

a. vector; the direction of the work vector b. scalar; the direction of the work vector

c. vector; whether the work adds or removes energy from the object d. scalar; whether the work adds or removes energy from the object

11. Which sets of units represent legitimate units for the quantity work? Circle all correct answers.

a. Joule b. N * m

c. Foot * pound d. kg * m/sec

e. kg * m/sec2 f. kg * m2/sec2

Helpful Hint!

The amount of work (W) done on an object by a given force can be calculated

using the formula:

W = F*d*cosΘ Where F is the force and d is the distance over which the force acts and Θ is the angle between F and d. It is important to recognize that the angle included in the

equation is not just any old angle; it has a distinct definition that must be remembered when solving such work problems.

Calculate!

12. For each situation below, calculate the amount of work done by the applied

force.

Diagram A Answer:

W = (100 N) * (5 m)* cos(0 degrees) = 500 J

The force and the displacement are given in the problem statement. It is said (or shown or implied) that the force and the displacement are both rightward. Since F

and d are in the same direction,the angle is 0 degrees.

Diagram B Answer:

W = (100 N) * (5 m) * cos(30 degrees) = 433 J

The force and the displacement are given in theproblem statement. It is said that the displacement is rightward. It is shown that the force is 30 degrees above the horizontal. Thus, the angle between F and d is 30 degrees.

Diagram C Answer:

W = (147 N) * (5 m) * cos(0 degrees) = 735 J

The displacement is given in the problem statement. The applied force must be 147 N since the 15-kg mass (Fgrav=147 N) is lifted at constant speed. Since F and d are

in the same direction, the angle is 0 degrees.

13. Before beginning its initial descent, a roller coaster car is always pulled up the first hill to a high initial height. Work is done on the car (usually by a

chain) to achieve this initial height. A coaster designer is considering three different angles at which to drag the 2000-kg car train to the top of the 60-

meter high hill. Her big question is: which angle would require the most work?___________________ Show your answers and explain!!!

Angle Force Distance Work

35° 1.15 * 104 N 105 m 1.18 x106 Joules

45° 1.41 * 104 N 84.9 m 1.18 x106 Joules

55° 1.64 * 104 N 73.2 m 1.18 x106 Joules

Be careful!

The angle in the table is the incline angle. The angle theta in the equation is the angle between F and d. If the F is parallel to the incline and the d is parallel to the incline, then the angle theta in

the work equation is 0 degrees. For this reason, W=F*d*cosine 0 degrees.

In each case, the work is approximately 1.18 x106 Joules.

The angle does not affect the amount of work done on the roller coaster car.

14. The following descriptions and their accompanying free-body diagrams

show the forces acting upon an object. For each case, calculate the work done by these forces; use the format of force • displacement • cosine(Θ).

Finally, calculate the total work done by all forces.

a. Only Fapp does work. Fgrav and Fnorm do not do work since a vertical force cannot cause a horizontal displacement. Wapp= (10 N)

* (5 m) *cos (0 degrees) = +50 Joules b. Only Ffrict does work. Fgrav and Fnorm do not do work since a

vertical force cannot cause a horizontal displacement. Wfrict =(10 N) * (5 m) * cos (180 degrees) = -50 Joules

c. Fapp and Ffrict do work. Fgrav and Fnorm do not do work since a vertical force cannot cause a horizontal displacement. Wapp = (10 N)

* (5 m) * cos (0 deg) = +50 Joules Wfrict = (10 N) * (5 m) * cos (180 deg) = -50 Joules

d. Neither of these forces do work. Forces do not do work when they

makes a 90-degree angle with the displacement. No work is done. e. Both Fgrav and Ftens do work. Forces do work when there is some

component of force in the same or opposite direction of the displacement. Wtens = (20 N)* (5 m) * cos (0 degrees) = +100 Joules

Wgrav = (20 N) * (5 m) * cos (180 degrees) = -100 Joules f. Same reasoning as part d

15. When a force is applied to do work on an object, does the object always

accelerate? __no________

a. Explain why or why not. if the force applied is in the direction opposite that the object is traveling, the

object will decelerate.

If the force applied is exactly equal in magnitude to frictional forces (and in the same direction of travel as the object), the object will remain at a constant velocity.

16. Determine the work done in the following situations. a. Jim Neysweeper is applying a 21.6-N force downward at an angle of

57.2° with the horizontal to displace a broom a distance of 6.28 m.

Go over in class w=f*d*cos(theta)

W=21.6 N*6.28m*cos(57.2)= 107.9 N*m

b. Ben Pumpiniron applies an upward force to lift a 129-kg barbell to a

height of 1.98 m at a constant speed.


W=129kg*9.81 m/s2*1.98m*cos(0)= 2506 N*m

c. An elevator lifts 12 occupants up 21 floors (76.8 meters) at a constant speed. The average mass of the occupants is 62.8 kg.


W=12*62.8kg*9.81 m/s2*76.8m*cos(0)= 567768 N*m

Power (CH 8 pg 104-105)

Review:

8. A force acting upon an object to cause a displacement is known as _____.

a. Energy b. Potential

c. Kinetic d. Work

9. Two acceptable units for work are ________. Choose two. a. Joule b. Newton

c. Watt d. Newton•meter

Power as a Rate Quantity:

10. Power is defined as the _______ is done.

a. amount of work which b. direction at which work c. angle at which work

d. the rate at which work 11. Two machines (e.g., elevators) might do identical jobs (e.g., lift 10

passengers three floors) and yet the machines might have different power outputs. Explain how this can be so.

The times it takes the elevators to lift—one might be faster

12. There are a variety of units for power. Which of the following would be fitting units of power (though perhaps not standard)? Include all that apply.

a. Watt

b. Joule c. Joule / second

d. Hp 13. Two physics students, Will N. Andable and Ben Pumpiniron, are in the

weightlifting room. Will lifts the 100-pound barbell over his head 10 times in one minute; Ben lifts the 100-pound barbell over his head 10 times in 10

seconds. Which student does the most work? ___same work___________ Which student delivers the most power? ____ben__________

Explain your answers.

Each lifts the same weight but ben does it much faster. Since we are worried about per second ben wins.

14. An often-used equation for power is Power = force*velocity Express an

understanding of the meaning of this equation by using it to explain what type of individuals would be the best choice for lineman on a football team.

Heavy people that can create a large force to

oppse.

Energy (CH 8 pg 105-111)

Definitions:

12.Potential energy is the ___potential_____________ energy of position

possessed by an object.

13.Kinetic energy is the energy of ____motion_____________.

14.The total amount of mechanical energy is merely the sum of the -___potential________ energy and the ___kinetic______________

energy. This sum is simply referred to as the total mechanical energy (abbreviated TME).

Calculate!

15.Read each of the following statements and identify them as having to do

with kinetic energy (KE), potential energy (PE) or both (B).

KE, PE or B? Statement:

KE i) If an object is at rest, it certainly does NOT possess this form of

energy. PE j) Depends upon object mass and

object height.

KE k) The energy an object possesses due to its motion.

B l) The amount is expressed using the

unit joule (abbreviated J).

PE m) The energy stored in an object due

to its position (or height).

PE n) The amount depends upon the arbitrarily assigned zero level.

KE o) Depends upon object mass and

object speed.

PE p) If an object is at rest on the ground

(zero height), it certainly does NOT possess this form of energy.

16.A toy car is moving along with 0.40 joules of kinetic energy. If its speed

is doubled, then its new kinetic energy will be _______. a. 0.10 J

b. 0.20 J c. 0.80 J

d. 1.60 J e. still 0.40 J

17.A young boy's glider is soaring through the air, possessing 0.80 joules of

potential energy. If its speed is doubled and its height is doubled, then the new potential energy will be _______.

a. 0.20 J b. 0.40 J c. 1.60 J

d. 3.20 J e. still 0.80

18.Which would ALWAYS be true of an object possessing a kinetic energy

of 0 joules? a. It is on the ground.




h. It is moving above ground level. 19.Which would ALWAYS be true of an object possessing a potential

energy of 0 joules?

a. It is on the ground. b. It is at rest.

c. It is moving on the ground d. It is moving. e. It is accelerating.


h. It is moving above ground level. 20.Calculate the kinetic energy of a 5.2 kg object moving at 2.4 m/s.

KE= ½ mv2

KE= ½ (5.2 kg) (2.4 m/s)2 =15 J

21. Calculate the potential energy of a 5.2 kg object positioned 5.8 m above

the ground.

PE=mgh

PE=5.2 kg*9.81 m/s2 *5.8m= 296 Nm

22. Calculate the speed of a 5.2 kg object that possesses 26.1 J of kinetic energy.

KE= ½ mv2

KE= ½ (5.2 kg) (x m/s)2 =26.1 J

x m/s = √26.1 J

½ (5.2 kg)= 3.17 m/s

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Lesson Plan on Energy Unit merged