Thrilling Experiments Friction -...

Teacher’s Guide

ThrillingExperiments

FrictionGrades 5-9

FTTV

CREDITS

Program Produc t ionSunburs t Vi sua l Media

Teacher ’s GuideRose Bu lau, M.Ed.Heather Ne l son

Pr in t Mater ia l Des ignDesk top Produc t ions

© 2004 Sunburst Visual Media, a division of Global Video, LLCHawthorne, NY 10532

Approximate running time: 19 minutes

Thrilling Experiments: Friction

© Sunburst Visual Media, a division of Global Video, LLC Thrilling Experiments: Friction

Table of Contents

Guide Information ....................................05

Fast Facts..................................................07

Before Viewing Activities ..........................08

During Viewing Activities ..........................12

After Viewing Activities ............................17

After Viewing Quizzes ..............................18

Additional Resources ................................21

Answer Keys ............................................26

Script........................................................37

5© Sunburst Visual Media, a division of Global Video, LLC Thrilling Experiments: Friction

About This GuideProviding students with visual media is an excellent way to take them out of the classroom and into the real world. Our programs offer real-world footage, dynamic graphics,engaging dramatizations, and first-person testimonials that keep students interested and helpthem visualize difficult concepts. More importantly, they reinforce critical learning objectivesshaped by state and national educational standards. However, the learning doesn’t begin andend when the program does. You can make the learning experience even more effective byusing the materials provided in this Teacher’s Guide.

GuideInformation

This guide is divided into the following sections:

• Fast Facts are designed to give your students a quick overview of the information presented within the video.

• Before Viewing Activities help identify what students already know about the subject, what they are curious about, and what they hope to learn.

• During Viewing Activities may be used during viewing to enhance students’ understanding of the video.

• After Viewing Activities help students summarize and draw conclusionsfrom the information that was presented.

• After Viewing Quizzes test students’ retention of the information presented in the program and activity sheets.

• Additional Resources are designed to help you extend the information presented in the program into other areas of your curriculum.

• Answer Keys are provided for relevant activities or reproducible pages.

• Script content is provided in an unabridged version for future reference.

Thrilling Experiments: Friction © Sunburst Visual Media, a division of Global Video, LLC6

GuideInformationProgram Overview

Thrilling Experiments: Friction focuses on the principle uses of friction. The information presented by the narrator reviews historical discoveries related to friction and delves into the three types of friction. The hands-on experiments demonstrate practical uses of friction in mechanical and other applications.

Viewing ObjectivesAfter viewing the DVD/video and utilizing the activities provided in the Teacher’s Guide, students will be able to:

• Understand and define key vocabulary words related to friction

• Describe and analyze motion of objects in two dimensions

• Solve problems involving angular motion

• Define, describe, and investigate forces

• Define, describe, and investigate three types of friction

© Sunburst Visual Media, a division of Global Video, LLC Thrilling Experiments: Friction7

Friction Fast Facts

• Friction is the force that acts between two objects that touch as they move past each other.

• A force is a push or a pull that acts on an object.

• Galileo studied force and made great contributions to physics.

• Three types of friction are rolling, sliding, and fluid.

• Rolling friction can be seen when gravity acts on a rolling ball.

• Sliding friction is the friction between two solid surfaces when they are in contact and slide over each other.

• Sliding friction produces the greatest amount of friction.

• Fluid friction is when objects move through fluids, like liquid or gas.

• Fluid friction produces the least amount of friction.

• Gravity is the force that keeps us on the ground.

• When friction is eliminated, machines can work more efficiently.

• Machines need ball bearings to help them work efficiently.

• The amount of force is measured in Newtons.

• Fluids act as lubricants.

Fast Facts

Thrilling Experiments: Friction © Sunburst Visual Media, a division of Global Video, LLC

Name

8

Before ViewingActivity 1

Word SplashEach of these words is related to friction. Write a paragraph using as many of these words as you can to explain what you know about friction.

hheeaattheat

Force

gravity

rolling friction

Galileo

frictionMachineMachine

newtons

bearings

spee

dsliding friction

e n e r g y

fluid friction


Name

9

Keep it SafeThe video you will see includes science experiments. In the bubble map below, list sixscience lab safety rules that will be important in completing any science experiment.


SCIENCESAFETY


Name

10


Truth or Untruth?Each pair of statements below contains one true statement and one untrue statement. Put a check mark next to the true statement in each pair.

1. Galileo was an italian astronomer who studied physics.

1. Galileo was a Greek philosopher who studied astronomy.

2. Force is a push that acts on an object.

2. Force is a push or pull that acts on an object.

3. There are five types of friction.

3. There are three types of friction.

4. Gravity does not come into play when working with friction.

4. Gravity comes into play when working with friction.

5. A skateboarder demonstrates principles of friction.

5. A skateboarder does not demonstrate principles of friction.

6. There is no friction present when a ball is rolling downhill.

6. There is friction present when a ball is rolling downhill.

7. Bearings are used to increase friction in machines.

7. Bearings are used to decrease friction in machines.

8. The amount of force needed to move an object is measured in Newtons.

8. The amount of force needed to move an object is measured in grams.


Name

11


Vocabulary ClozeVocabulary words that you will see and hear in the video are listed in the box below. Thewords fit in the sentences below. Match each word with its corresponding sentence andwrite the word in the blank.

1. A ___________________ is a push or pull that acts on an object.

2. ___________________ is the force that acts between two objects that touch as they

move past each other.

3. Galileo destroyed the notion that force is necessary to keep objects ___________________

by pointing out how the planets move around the sun.

4. Force can start or stop ___________________ , as well as reduce or increase

the speed.

5. Three types of friction are rolling, ___________________ , and fluid.

6. Ball ___________________ make wheels roll well.

7. Sliding friction ___________________ down motion.

8. The amount of force needed to move an object is measured in ___________________ .

9. The best ___________________ are the ones that eliminate friction.

bearings

Newtons

sliding

lubricants

friction

moving

slows

force


Name

12

During ViewingActivity 1

Friction FactsAs you view the video, pay close attention to the information about Galileo. Use the chart below to record important information about this great scientist.

When did he live?

What idea did he argue?

What did he study?

Where did he live?

What did he point to?

What field of science was his specialty?


Name

13


Friction ExplanationsIn the video, demonstrations are presented which outline the different types of friction. Usethe information presented in the video to complete the following organizers about each typeof friction.

materials used:

demonstration diagram:

what happened?

ROLLING FRICTION DEMONSTRATION

materials used:


what happened?

SLIDING FRICTION DEMONSTRATION

materials used:


what happened?

FLUID FRICTION DEMONSTRATION

Name During ViewingActivity 3

Fickle FictionIn one experiment on the video, the friction was changed from sliding to rolling. The steps for this experiment are listed below, but they are out of order. Number the steps in the correct order by writing the appropriate number on each line. Then, answerthe question at the bottom of the page.

stick the pencil to the plastic lid using another ball of clay in the center of the pencil

try to spin the lid on the can a second time

place a ball of clay on each end of the pencil

try to spin the lid on the can

place the marbles on top of the can

gather materials – a soup can, some marbles, a pencil, some clay, and a plastic lid

place the lid and pencil on top of the marbles

take the lid and the pencil off the can

Which step caused the change in friction from sliding to rolling?

Write a sentence that proves your answer.


Name During ViewingActivity 4

Real World FrictionThroughout the video, references are made friction and how it applies in our real lives.Listen for information that is needed to complete each of the thoughts below. Write in themissing information as you hear it and see it.

Have you ever been walking down the sidewalk and slipped on some ice? The sidewalk normallycreates ___________________ with your shoes. This didn’t happen with the ice covering the sidewalk.

When you are skateboarding and you use your foot to push yourself faster, you use ___________________ .

When you pull a door closed, you use ___________________ .

Roads, your hands, and the seat you are sitting in all have some form of ___________________ .

Every smooth surface has microscopic irregularities that can ___________________ down an object.

A skateboarder on a half-pipe speeds up as he goes down, demonstrating ___________________ .

As the skateboarder goes up the half-pipe, he ___________________ .

As the skateboarder drops into the half-pipe and speeds up, then he rolls up the other side and ___________________ .

The skateboarder relies on ___________________ in the wheels to make the wheels rotate moresmoothly, allowing him to roll down the ramp faster.

Machines need ___________________ to allow them to work more efficiently.

When you are running on the grass and you fall, you ___________________ on the grass a little, thencome to an abrupt halt.

An airplane in the sky uses ___________________ friction as it encounters air resistance.

Look at your shoes. You’ll notice that the tread on your shoes is meant to ___________________ the amount of friction beneath you to keep you and your feet on the ground.



Name

16


Friction FormulationsWhile watching the video, find out about the three types of friction. Find out what each type of friction is, how it is produced, and how it is used. Record the information youuncover below.

how is it produced?

how is it used?

how is it produced?

how is it used?

how is it produced?

how is it used?

Name After ViewingActivity 1


Friction FindsTime to investigate! Have teams of students complete the following steps:

1. Gather materials. Each team should have balls of different sizes and weights, a book, and a sheet of cardboard the same length and width as the book. They should also

have objects such as a feather or a piece of paper that encounter more air resistance when dropped than the other objects.

2. Ask your students if they predict that a heavier or larger object, if dropped from a height, will fall to Earth faster than a lighter or smaller object. Tell them that Galileo Galilei (1564-1642) performed a famous experiment that they are going to replicate

in order to confirm or refute their predictions. Have students record their predictions.

3. At this point, students can research on the internet or in an encyclopedia to find out more about Galileo’s experiment in which he dropped objects from the Leaning Tower of Pisa in Italy.

4. Have students experiment with the materials they have been given. Record results.

5. Teams of students should then meet and design their own experiments. Remind them that a good experiment should have a control and introduce only one variable at a time. Each group’s experimental design should include a chart on which to record the results of each test performed.

6. Have students experiment with the object pairs, dropping them, one at a time, from a safe and secure position of height. Other students in the group should observe closely to see whether one object reached the floor before another or if both objects reached the floor at the same time. Students should carefully record their results on the charts they have previously created.

7. Continue with a discussion about where the friction occurs in the experiments and what kind of friction is involved.


Name

18

After ViewingQuiz 1

Vocabulary QuizMatch each vocabulary word with its correct definition. Draw a line to connect the wordwith its definition.

bearings • • power

friction • • material that provides a smooth film over

an object

Newtons • • a part of a machine on which another part

revolves

sliding • • rubbing of one object against another

lubricant • • a type of friction in which two objects slide

over each other

force • • unit of force

On the lines below, use at least three of the words from above to write

what you have learned about friction from watching the video.

Name After ViewingQuiz 2

Fact QuizFill in the blanks.

1. Cars being driven on icy roads can have better traction if they have chains on their

tires because chains increase the ___________________ between the tires and the road.

2. Wheeled luggage is easy to pull because ___________________ friction is lower than

___________________ friction.

3. The unit of force is ___________________ .

4. A ballet dancer uses rosin powder on her shoes to increase ___________________ .

6. Which term means “resistance to motion”?

7. Which occurs between two surfaces that touch but do not move in relation to each other?

8. Which occurs between the surface of a wheel or other round object and another surface?

9. Which occurs when one object or surface slides over another?

a. pressure b. inertia c. friction d. momentum

a. static friction b. sliding friction c. rolling friction d. fluid friction



Multiple Choice:


After ViewingQuiz 2

Fact Quiz (cont.)Multiple Choice:

10. Of which type of friction is the following an example?

A dolphin swimming through the ocean

11. Which is the strongest friction?

12. Which produces the most heat and wear on the surfaces involved?

13. Which is NOT used to reduce friction?

14. Friction keeps things from sliding or slipping?

14. Friction is needed to slow things down or stop them?

a. static b. sliding c. rolling d. fluid



a. lubricant b. wheels c. smooth surface d. cleats

a. true b. false

a. true b. false

Name



Extensions AdditionalResources

• Swinging PendulumsOne of Galileo’s key experiments involved observing pendulums. Using a variety ofdifferent lengths and weights, he carefully noted each pendulum's period (the amountof time it takes for a pendulum to make one complete swing). Galileo’s observationsallowed him to determine that the period of a pendulum’s swing is affected by itslength but not its weight—an observation that may run counter to what studentsintuitively expect. To begin this activity, lead a class discussion about the fact thatscientists cannot rely on intuition alone, but must perform experiments to test theirhypotheses. Ask your students to replicate Galileo’s pendulum experiments usingvarying lengths of string with different numbers of washers attached to the ends.Students should measure each pendulum’s length, weight, and period, making surethat they keep the amplitude, or angle to which the pendulum is raised, consistent.When their observations are complete, gather their data into a chart for easyreference.

• Construct Lego CarsHave teams of students or individual students construct cars out of Legos. Designsshould include types of wheels and surfaces that relate to the types of friction studied.Students design, build, and test the cars. Students should then test the cars on avariety of surfaces.

• Junkyard Wars:The Discovery Channel has many activities related to friction. You can tie in classroomactivities with the Junkyard Wars series. A variety of “junk” can be provided to teamsof students who build apparatuses that involve the study of friction. For example, onechallenge might be to build the apparatus that provides the greatest amount of frictionwhen pulled with a spring.

• Static Versus Sliding Friction:Provide teams of students with heavy books, aluminum foil, wax paper, plastic bags,sandpaper, copy paper, string, tape, and spring balances. Present the problem to thestudents - which wrapped book will be the hardest to pull, which will be the easiest topull? Have the students, as a group, order the wraps from hardest to easiest. Studentswill then experiment with the equipment to find the right order of wrappings, thedifference between static (starting) friction and sliding friction, and whether there is adifference when the book is turned on edge versus flat on the table.


AdditionalResources Extensions

• Air Resistance and AccelerationAsk your students to use a stopwatch to measure the time it takes a freely rolling toy car to roll from the top to the bottom of a slightly inclined board. Instructthem to record their times. Ask students if the car appears to be rolling with aconstant speed or accelerating. Then have students cut three squares out of a stiff piece of cardboard, making one square 5" x 5", one 10" x 10", and one 20" x 20". Have them fasten the 10" x 10" square onto the front of the toy car so that the plane of the square is perpendicular to the forward motionof the car. Next, have students measure and record the time it takes their “sail car” to roll from the top to the bottom of the same inclined board. Instructstudents to make a diagram of each part of the experiment, representing each forceand counter force acting on the car with a labeled arrow indicating the force’sprobable direction. Students should use their diagrams to explain differences in thetimes they recorded, both with and without the “sail.” Students can then use similardiagrams to predict what will happen when they replace the first cardboard “sail”with the other two and conduct experiments that will test their hypotheses.


Suggested Reading List AdditionalResources

Arnold, Nick. Fatal Forces. Scholastic, 1997. Science is fun when this college professor explains physical forces so that evennonscientists can understand them. Lots of humor and lots of cartoons make this anentertaining, informative volume.

Cook, Nick. Roller Coasters, or, I Had So Much Fun I Almost Puked. Carolrhoda Books, 1998. It’s all here – the history of coasters, the physics that make them work, different types of roller coasters, and how they were designed and constructed. There are great pictures,easy-to-understand explanations, and even a section on tips for a scarier ride.

Feynman, Richard. Six Easy Pieces: Essentials of Physics Explained by Its Most Brilliant Teacher. Addison-Wesley Publishing Company, 1995.

This witty discussion of gravity, written without equations and technical jargon, is an idealintroduction to the concept written by one of the most admired and accessible scientists ofour time.

Feynman, Richard. The Character of Physical Law. MIT Press, 1994. Fascinating writing by a truly great scientist—gravitation is Richard Feynman’s principlelaw in this outstanding book. His approach and enthusiasm for the subject makes this titleclassic reading in the field.


AdditionalResourcesSuggested Reading List

Gardner, Robert. Experiments with Motion. Enslow, 1995. Easy-to-do experiments better illustrate the text and allow a student to understandNewton’s Laws of Motion and their application to space flight as well as to the movementof animals and vehicles. Diagrams, explicit lists of materials needed, answers to puzzles,and a bibliography contribute to the usefulness of this work.

Morgan, Sally and Adrian. Movement. Facts on File, 1993. Animals have adapted over many thousands of years to move successfully; man has studied and put to use the design of animals to make machines that move. The experimentsprovided in this book allow a better understanding of both animals and machines and theforces that affect their movement. An index, glossary, and answers to questions areincluded.

Shafer, Mike and Scott Rutherford. Roller Coasters. MBI Publishing, 1998. This book includes a history of roller coasters and sidebars explaining how they work, butprimarily gives region-by-region information on the best coasters in the United States.Included are the location, length, age, and features of each. The authors also provide anunofficial top-twenty ranking of the best-of-the-best.

Wood, Robert W. Mechanics Fundamentals. Learning Triangle Press/McGraw-Hill, 1996.

Important principles of physics, specifically relating to the effect of forces on objects at restor in motion, are explained through the simple-to-perform experiments in this book. Linedrawings illustrate all experiments and a glossary explains new terms.


Internet Sites AdditionalResources

Below is a list of sites that you may use to find more information about friction. Due toroutine web maintenance, not all of the links will be accurate at the time of access. If the link is not available, try to conduct a search on that topic from the main site or from a search engine.

Exploring GravityAn introductory, intermediate and advanced online tour of our understanding of gravityfrom ancient times to theoretical constructs like black holes. Check your knowledge of thephenomenon with the online gravity test.http://www.curtin.edu.au/curtin/dept/phys-sci/gravity/index2.htm

Amusement Park Physics: Roller CoasterRead about the principles for designing roller coasters and then immediately apply thisknowledge by designing and testing your own online roller coaster. This hands -on website puts your knowledge of gravitational potential energy to work.http://www.learner.org/exhibits/parkphysics/coaster.html

Inventing the Scream MachineWhen were they invented? How have they changed? Who are the heroes of the roller coaster industry? Starting in the 18th Century, follow the historical evolution of the modern roller coaster on this clickable and informative roller coaster historytimeline.http://coasters.eb.com/

Discovery Channel: Thrills, Chills & SpillsTop ten coasters, coaster webcam, coaster crosswords, coaster history, and design your own coaster. If you’ve got the stomach for such thrills, chills and spills, Discovery Online has it all.http://www.discovery.com/exp/rollercoasters/thrills/thrills.html


Answer Key - Before Viewing Activity Sheet 2

Keep it SafeAnswers may vary

SCIENCESAFETY

Follow laboratoryprocedures.

Never attempt an

experiment without the

proper supervision.

Never attempt an

experiment without the

proper supplies.

Follow the instructions

of your teacher or

lab manager.

Prepare materials and

safety equipment before

beginning the experiment.

Wear safety goggles and

other appropriate safety

equipment as needed.



Truth or Untruth?Each pair of statements below contains one true statement and one untrue statement. Put a check mark next to the true statement in each pair.

1. Galileo was an italian astronomer who studied physics.

1. Galileo was a Greek philosopher who studied astronomy.

2. Force is a push that acts on an object.

2. Force is a push or pull that acts on an object.

3. There are five types of friction.

3. There are three types of friction.

4. Gravity does not come into play when working with friction.

4. Gravity comes into play when working with friction.

5. A skateboarder demonstrates principles of friction.

5. A skateboarder does not demonstrate principles of friction.

6. There is no friction present when a ball is rolling downhill.

6. There is friction present when a ball is rolling downhill.

7. Bearings are used to increase friction in machines.

7. Bearings are used to decrease friction in machines.

8. The amount of force needed to move an object is measured in Newtons.

8. The amount of force needed to move an object is measured in grams.

✔

✔

✔

✔

✔

✔

✔

✔



Vocabulary ClozeVocabulary words that you will see and hear in the video are listed in the box below. The words fit in the sentences below. Match each word with its correspondingsentence and write the word in the blank.

1. A ___________________ is a push or pull that acts on an object.

2. ___________________ is the force that acts between two objects that touch as they

move past each other.

3. Galileo destroyed the notion that force is necessary to keep objects ___________________

by pointing out how the planets move around the sun.

4. Force can start or stop ___________________ , as well as reduce or increase

the speed.

5. Three types of friction are rolling, ___________________ , and fluid.

6. Ball ___________________ make wheels roll well.

7. Sliding friction ___________________ down motion.

8. The amount of force needed to move an object is measured in ___________________ .

9. The best ___________________ are the ones that eliminate friction.

bearings

Newtons

sliding

lubricants

friction

moving

slows

force

force

Friction

moving

motion

sliding

bearings

slows

lubricants

Newtons


Answer Key - During Viewing Activity Sheet 1

Friction FactsAs you view the video, pay close attention to the information about Galileo. Use the chart below to record important information about this great scientist.

mid 1600’s

When did he live?

That force is necessary

to keep objects moving.

What idea did he argue?

force

What did he study?

Italy

Where did he live?

How the planets move

around the sun.

What did he point to?

physics

What field of science was his specialty?



Friction FindsIn the video, demonstrations are presented which outline the different types of friction. Use the information presented in the video to complete the following organizersabout each type of friction.

materials used: flat surface, ramp 2-3 feet long, plastic ball

demonstration diagram:diagram should show materials arranged as seen in the video

what happened? the ball gains speed as it goes down the ramp, the ballloses speed as it goes up the ramp, and the ball comes to a stop on the table

ROLLING FRICTION DEMONSTRATION

materials used: a textbook, string, spring scale that measures Newtons, carpeted and tiled hallway, roll of waxed paper, 3 pieces of sand paper, masking tape


what happened? the amount of force needed to drag the book acrossthe carpet was greater than that needed to drag it across the tile

SLIDING FRICTION DEMONSTRATION

materials used: plastic or wood container 3 feet long, polystyrene foam block,rock, string, spring scale, cooking and automotive oil, water


what happened?water was the least lubricating fluid, motor oil was better,and cooking oil was best.

FLUID FRICTION DEMONSTRATION



Fickle FictionIn one experiment on the video, the friction was changed from sliding to rolling. The steps for this experiment are listed below, but they are out of order. Number the steps in the correct order by writing the appropriate number on each line. Then, answerthe question at the bottom of the page.

3 stick the pencil to the plastic lid using another ball of clay in the center of the pencil

8 try to spin the lid on the can a second time

2 place a ball of clay on each end of the pencil

4 try to spin the lid on the can

6 place the marbles on top of the can

1 gather materials – a soup can, some marbles, a pencil, some clay, and a plastic lid

7 place the lid and pencil on top of the marbles

5 take the lid and the pencil off the can

Which step caused the change in friction from sliding to rolling?step number 6

Write a sentence that proves your answer.responses here should include some references to the marbles

acting as ball bearings and reducing the amount of friction



Real World FrictionThroughout the video, references are made to how friction applies in our real lives. Listen for information that is needed to complete each of the thoughts below. Write in the missing information as you hear it and see it.

Have you ever been walking down the sidewalk and slipped on some ice? The sidewalk normallycreates ___________________ with your shoes. This didn’t happen with the ice covering the sidewalk.

When you are skateboarding and you use your foot to push yourself faster, you use ___________________ .

When you pull a door closed, you use ___________________ .

Roads, your hands, and the seat you are sitting in all have some form of ___________________ .

Every smooth surface has microscopic irregularities that can ___________________ down an object.

A skateboarder on a half-pipe speeds up as he goes down, demonstrating ___________________ .

As the skateboarder goes up the half-pipe, he ___________________ .

As the skateboarder drops into the half-pipe and speeds up, then he rolls up the other side and ___________________ .

The skateboarder relies on ___________________ in the wheels to make the wheels rotate moresmoothly, allowing him to roll down the ramp faster.

Machines need ___________________ to allow them to work more efficiently.

When you are running on the grass and you fall, you ___________________ on the grass a little, thencome to an abrupt halt.

An airplane in the sky uses ___________________ friction as it encounters air resistance.

Look at your shoes. You’ll notice that the tread on your shoes is meant to ___________________ the amount of friction beneath you to keep you and your feet on the ground.

friction

friction

slow

slows down

slows down

ball bearings

ball bearings

slide

fluid

increase

gravity

force

force



Friction FindsWhile watching the video, find out about the three types of friction. Find out what each type of friction is, how it is produced, and how it is used. Record the information you uncover below.

how is it produced? produced by rolling ball down the ramp

how is it used?

how is it produced? between two solid surfaces

how is it used? sliding down the slide, across the grass

how is it produced? requires a lubricant

how is it used? airplanes, machinery

rolling friction

sliding friction

fluid friction


Answer Key - After Viewing Quiz 1

Vocabulary QuizMatch each vocabulary word with its correct definition. Draw a line to connect the word with its definition.

bearings • • power

friction • • material that provides a smooth film over

an object

Newtons • • a part of a machine on which another part

revolves

sliding • • rubbing of one object against another

lubricant • • a type of friction in which two objects slide

over each other

force • • unit of force

On the lines below, use at least three of the words from above towrite what you have learned about friction from watching the video.

answers will vary but responses should accurately reflect the definitions above



Fact QuizFill in the blanks.

1. Cars being driven on icy roads can have better traction if they have chains on their

tires because chains increase the ___________________ between the tires and the road.

2. Wheeled luggage is easy to pull because ___________________ friction is lower than

___________________ friction.

3. The unit of force is ___________________ .

4. A ballet dancer uses rosin powder on her shoes to increase ___________________ .

6. Which term means “resistance to motion”?

7. Which occurs between two surfaces that touch but do not move in relation to each other?

8. Which occurs between the surface of a wheel or other round object and another surface?

9. Which occurs when one object or surface slides over another?

a. pressure b. inertia c. friction d. momentum




Multiple Choice:

friction

fluid

rolling

Newton

fluid friction



Fact Quiz (cont.)Multiple Choice:

10. Of which type of friction is the following an example?

A dolphin swimming through the ocean

11. Which is the strongest friction?

12. Which produces the most heat and wear on the surfaces involved?

13. Which is NOT used to reduce friction?

14. Friction keeps things from sliding or slipping?

14. Friction is needed to slow things down or stop them?




a. lubricant b. wheels c. smooth surface d. cleats

a. true b. false

a. true b. false


Script

TONYHello, and welcome to Thrilling Experiments! I am your host Tony “Thrill” Hill. I am so excited you could join me today because we get to perform some verythrilling experiments on friction.

Have you ever been walking down the sidewalk and slipped on some ice? All of a sudden, your feet lose traction and you fall. OUCH! Well, that is friction at work. Amazing isn’t it!

So what is friction exactly? Well, friction is the force that acts between 2 objectsthat touch as they move past each other. Remember the sidewalk you werewalking on? It normally creates a friction with your shoes, which allows you to notslip when you walk? But when the ice covered the sidewalk, the friction betweenyour feet and the sidewalk largely decreased, and you slipped. Whoa!

Before we get to friction though we must understand some facts on force. What is force and how is it related to friction. (With the voice sounding like DarthVader) “Use the force!” Well, not that kind of force. Actually, a force is a push orpull that acts on an object.When you are skateboarding and you use your foot topush yourself faster, you use force. When you pull a door closed, you use force.Force is what moves these objects.

Scientists have been studying force for years. In the mid-1600’s an Italianastronomer, Galileo Galilei, studied force and made great contributions to physics.He destroyed the notion that force is necessary to keep objects moving by pointing out how the planets move around the sun.

CASTTony “Thrill” Hill ..............................................................hostJune Sifuentes......................................................experimenterChris ............................................................................volunteerJilyane ........................................................................volunteer


Script

TONYWe now know that force can start or stop motion, as well as reduce or increase thespeed of motion. When force reduces the speed of motion, it is called friction.

You see all surfaces have some sort of friction. Roads, your hands, and the seat you are sitting in all have some form of friction. Even very smooth surfaceshave microscopic irregularities that can slow down an object. Like the ice youslipped on. Interesting huh!

There are 3 types of friction: Rolling, sliding, and fluid. In order to betterunderstand friction, we are going to perform some experiments. But before we do, we need to review the safety rules in the laboratory. Never attempt ANY experiment without proper supervision and equipment. Always wear your safety goggles while in the laboratory.

Now lets get on to the experiments. I think we might need some expert help. So Iinvited, oh, yes, here she is - June Sifuentes. It’s great to see you again!

JUNEHello Tony! Thanks for inviting me. I heard you mention there are 3 types of friction. What was the first one?

TONYLets see…rolling friction.

JUNE Very good! To better demonstrate rolling friction, we are going to recreate anexperiment that Galileo performed. Tony do you know what the experiment is?

TONYYou bet I do! Galileo believed that when friction is present there is a force neededto keep an object in motion. Right?

JUNE That’s right, Tony. Good job.


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EXPERIMENT #1: FRICTION AND FORCE

TONYWhat do we need to do our first experiment?

JUNE Well, we’ll need: a flat surface, like a table, a ramp that is 2-3 feet long and a foot height, and a plastic ball.

TONYCool, lets get started. But before we do lets put our safety goggles on just in casesomething happens.

JUNE That’s right! The first thing you need to do is set your ramp up. Don’t make it toosteep. Now, take your plastic ball and roll it DOWN the ramp. Note the speed ofthe ball. What is happening to the ball, Tony?

TONYIt is gaining speed as it goes down the ramp.

JUNEYes! That is because the ball is moving with, and in the same direction as gravity.Remember what gravity is?

TONYAh, yes. Gravity! It is the force that keeps us on the ground. This reminds me of askateboarder on a half-pipe ramp. As he goes down, he speeds up.

JUNEVery good, Tony. Next, reverse the first part of the experiment and roll the ball UPthe ramp. Remember to note the speed. What do you think will happen, Tony?


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TONYUH…let’s see. I think it will slow down. Just like the skateboarder, as he goes upthe ramp, he slows down. Is it due to gravity as well?

JUNEYes! The ball is moving in the opposite direction of gravity just like theskateboarder. The gravity is pulling the ball back towards the ground. Now letsroll the ball on a flat surface. What happens?

TONYIt continues to move along the table. But it is slowing down. Why?

JUNEWell Tony, the ball is in contact with the table and therefore it has some friction. Theball comes to a stop when all the energy is used up.

TONYAmazing stuff! Now lets see if I have this correct. Just like the ball, theskateboarder drops into the half-pipe and speeds up, then he rolls up the other side slowing down.

JUNEVery good. What this proves is that gravity is a force that acts upon the ball. Whenthe ball is rolling down the ramp, you can see that gravity works in a downwarddirection because it speeds up the balls motion. When the ball is rolling up theramp, gravity acts as a frictional force, which slows the ball down. And when theball is moving on a flat surface, gravity keeps it on the table.

TONYI have a question. When the ball is rolling downward is there any friction?

JUNEThat is a very good question, Tony. When the motion is in downward direction, theeffect of friction, in this case, is negligible. Meaning it is very, very, very small.


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TONYThere you have it in a nutshell. WOW, we got to see gravity at work as a forcethat pulls and as a frictional force that slows motion. Pretty cool. What else canwe do, June?

EXPERIMENT #2: DEMONSTRATING FRICTION

JUNE We can do an experiment where we can see friction at work and how it can make machines work more efficiently when it’s eliminated.

TONYALL RIGHT! Lets do it!

JUNE Ok, here are the items you will need to complete the experiment. A soup can, filledor empty, some marbles, a pencil, some clay, a plastic lid that fits over the can, anda volunteer.

TONYAll right. Here’s our volunteer. What’s your name?

CHRISI’m Chris. What are we going to do with all this stuff?

JUNE We are going to demonstrate friction and how eliminating it can make machineswork much more efficiently.

TONYIt’s like how ball bearings make wheels roll better. Look at the skateboarder on the ramp. The wheels have ball bearings inside which rotate around the axle.This makes the wheel rotate more smoothly and allows the skateboarder to rolldown the ramp faster.


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JUNEExactly! This experiment will show how that works. Ok, Chris, place a ball of clayon each end of the pencil. Next, stick the pencil to the plastic lid using another ballof clay in the center of the pencil. Place the lid on the can. Now try to spin the lidon the can. How well does it spin?

CHRISNot very good. Is that what is supposed to happen?

JUNEThat is exactly what is supposed to happen. Now take the lid and the pencil offthe can and place the marbles on top of the can. Place the lid and pencil on top ofthe marbles. Anything different?

CHRISWow! This is amazing. The pencil spins much faster. What happened to thefriction?

JUNEThe marbles eliminated the friction. By placing the marbles between the lid andcan, we changed the friction from sliding to rolling. Remember the skateboarder?The bearings in his wheels are like the marbles on the can. Without them he wouldnot move very fast, because the inside of the wheel would slide against the axlebolt.

CHRISCool.

JUNEThe purpose of the experiment was to show that friction could be eliminated (or mostly decreased) with ball bearings. Machines need ball bearings to allowthem to work efficiently. Thank you for your help, Chris. Ok, Tony, lets move on to

another type of friction. What types of friction are left, Tony?

TONYLets see…sliding and fluid friction.


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JUNEExactly, Tony. The next thrilling experiment is going to be on sliding friction.

TONYLike when you slide down the “slip and slide”.

JUNEYep! Sliding friction is the friction between two solid surfaces when they are in contact and slide over each other. It slows motion down. This produces themost friction.

TONYOh yeah, just like when you are running on grass and fall. Your knees hit the grass, slide on it a little, and then come to an abrupt halt. Boy that hurts.The friction between your knees and the grass is sliding friction, correct?

EXPERIMENT #3: SLIDING FRICTION

JUNEExactly! In this next experiment we are going test different types of flooring and surfaces. Are you ready, Tony?

TONYOh yeah, let’s get the friction working. What are we going to need for thisthrilling experiment?

JUNEFirst, you will need a somewhat heavy book, like a text book, some string, a spring scale that measures Newton’s, a carpeted hallway, a tiled hallway, some wax paper, 3 pieces of rough sand paper, and some masking tape.

TONYAll right, I have my items what do we do next?


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JUNEFirst you tie a piece of string around the book, like a ribbon on a present. Next you place the book flat on the carpet surface. Hook the spring scale to thestring on the book. Pull gently! Once the book is moving keep it moving in aconstant motion. Note the constant reading on the scale. Do this several timesto get an accurate average force.

TONYThe reading on the scale indicates the amount of force needed to move the book.It’s 1.5 Newton meters.

JUNERight! That is the force needed to overcome the friction and keep the book inmotion. Next, drag the book and scale on the tiled floor, or a large smoothsurface like this lab table. What is your reading, Tony?

TONYMine is lower than the reading from the carpet. It’s .5 Newton-meters.

JUNEPerfect! The reading is much lower because there is less friction between the tiled surface and the book. Now take the wax paper and tape it down to thesurface. Repeat the experiment by dragging the book over the wax paper. Do the same with sand paper. Is there any difference?

TONYLets see. The wax paper was .75 Newton meters and the sand paper was 2.5Newton meters. The sand paper has more friction.

JUNEGood job! Now that we have covered rolling and sliding friction we need to do some experiments on fluid friction. Fluid friction produces the least amountof friction of the 3 types of friction.

TONYFluid friction is when objects move through fluids, like liquid or gas. An airplanein the sky uses fluid friction as it encounters air resistance.


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JUNEThat’s right. Another example is when oil runs through machines and engines.That is fluid friction at work. A lot of times, the lubricants are used to reducefriction. We are going to look at that.

TONYThis sounds interesting. What do we need, June?

EXPERIMENT #4: FLUID FRICTION

JUNEThis is going to be fun! We need a container that is 3 feet long and 1 foot wide, a polystyrene foam block, a rock, some string, the spring scale from the last experiment, cooking oil, automotive oil, water, and a volunteer.

TONYHi. What’s your name?

JILYANEJilyane. This looks kind of messy.

TONYYeah it does. We have a lot of different oils here. This is getting better everyminute. What’s next, June?

JUNE In this experiment we are going find out which fluid is the best lubricant or the one that eliminates the greatest amount of friction. First thing you need todo, Jilyane, is to create a pathway of wood or plastic. A long plastic containerwill work fine. The polystyrene foam block should be able to float on the liquidbeing tested.


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JUNE Take the string and tie it around the foam. Then take the spring scale and connectit to the string. Pour the first liquid in, which is the water. Make sure there is enough to cover the entire surface of your container. Place thepolystyrene foam block on the surface of the oil, and put the rock on top of it. Now,pull the block across the water with the spring scale. Note the reading on the scale.

JILYANE This is pretty cool stuff. There is some resistance. It’s .75 newton-meters

TONYFluid Friction at work.

JUNE Now pour the cooking oil into the container and repeat the exercise. Note thereading on the scale. Any difference?

JILYANEYes, there is less friction with the cooking oil than the water. It’s .25 newton-meters

JUNENow repeat the same exercise with the motor oil. Is there any change in the fluid friction?

JILYANEYes. The motor oil doesn’t eliminate the friction as much as the cooking oil. It’s .40newton-meters. Water is definitely the least lubricating.

JUNEJilyane, great job. That was a lot of fun. Experimenting is one of the best ways tounderstand science. Friction is all around us at all times. The next time you slip,remember, it’s because there was not enough friction between your feet and theground.


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TONYYeah, and the next time you are out on the basketball court or baseball field, look at the bottom of your sneakers. You’ll notice the tread of your shoes is meantto increase the amount of friction beneath you to keep you and you feet on the ground.

JUNEWell, I hope you enjoyed those thrilling experiments. I sure did. I love to explorethe questions of science. See you next time.

TONYBye, (in a darth vader voice) “and may the friction be with you. Always!

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