work and science machines · 2019-10-20 · work and machines science activities session 1...

machine • work • lever • exert • apply • load • force • effort • specifications

SciGen Unit 8.2

WORK AND MACHINES

SCIENCE ACTIVITIES

Session 1 Reader’s Theater

2–4

Session 2 Speaking Scientifically

5–9

Session 3 In the Lab

10–11

Session 4 A Closer Look at Levers

12–14

Session 5 Writing

15–16

SUPPLEMENTARY ACTIVITIES FOR OTHER CONTENT AREAS

ELA It Was a Dark and Stormy Night…

17

Math Algebraic Equations Related to Levers

18

Social Studies Are Pulleys a Thing of the Past?

19–20

FOCUS WORDS

Examining the Focus Words Closely 21

science

© 2015 SERP SciGen Unit 8.2 1


Hamza: I never have the energy to do my homework.

Olivia: I keep telling you, Hammy, that’s an attitude problem, not an energy problem.

Hamza: I wish I had a machine to do all that work for me.

Cooper: If you had done your homework, you’d know what work machines really do. Hint: not homework.

Hamza: If you say so, Nerd Cooper. What is this “work” that machines do?

Olivia: I thought work was what energy did.

Hamza: (sarcastically) Is your name Nerd Cooper?

Cooper: Be nice. And she’s right. Work is when you change how something is moving: speed it up, slow it down, change its direction or how it's spinning—like when you kick a soccer ball.

Olivia: See Hamza, work can be fun!

Cooper: Basically it can be any movement that lines up with a push or pull. I mean that’s the science term “work.” But in everyday English we use the word “work” for a lot of different things.

Hamza: So, scientifically speaking, if I kick a ball and the ball knocks over a chair, I did the work of making the ball go, and then the ball did the work of knocking over the chair?

Cooper: Hmmm...

Olivia: I think so, Ham. You had energy from eating food, and then you exerted a force when you kicked the ball. Your kick gave energy to the ball, and the ball used the energy to knock over the chair.

Cooper: It’s cool to think about how something simple like kicking a ball has all these things going on.

Hamza: (daydreaming) I’m a machine on the soccer field.

Olivia: Well, they actually don’t allow machines on a soccer field, but they do in a hockey rink.

Hamza: You mean the Zamboni machine that smoothes the ice?

Cooper: Actually, she’s talking about the hockey stick.

Olivia: And you would know that if...

Hamza: I know! I know! If I did my homework. Wait, how is a stick a machine? It doesn’t take gas or electricity. That can’t be right.

Cooper: It is a machine! The way to figure it out is to think about whether it can transmit work.

Olivia: Coop, did you get the thing on the homework about pretending your pencil was a windshield wiper?

Hamza: What!? Oh great. Now I’m curious. I can’t believe I’m curious about homework. What have you two done to me?

Cooper: Here. Try it. Hold your pencil in front of you by the end and shift it back and forth like a windshield wiper.

A small motion of your fingers causes a large motion at the other end of the pencil. That means it’s a machine. A lever to be exact.

Hamza: Oh, that’s kind of cool. I see the connection to the hockey stick. A player moves the stick at one end, but the stick moves a lot more at the other end and applies force to the puck so it goes faster than the hand moves. Wham!

Olivia: I guess golf and baseball are similar. They use levers. But I know people think of machines as things like cars or elevators. Not sticks.


Speaking ScientificallyReader's Theater

Session 1

Modern Levers

Setting: Cooper, Olivia, and Hamza are hanging out in the library working on their homework.


Cooper: Well, it’s not that cars and elevators aren’t machines. They’re more like a bunch of machines put together into a complex machine. Look:

Cooper sketches a car and an elevator.

Hamza: I get the wheels on a car, but you mean when I’m in an elevator it’s held up with a string?

Olivia: A strong string. More like a metal cable. And the pulley is like a version of the wheel.

Hamza: Stop! I don’t think I want to know all this stuff. What if the cable breaks?

Cooper: It won’t break if you respect the load limit. It’s posted inside the elevator.

Olivia: Even if you overload an elevator, I bet it would be okay. Engineers and scientists study specifications carefully for safety.

Hamza: They better, or else I’m taking the stairs!

Cooper mentions “work,” but he says that there’s a scientific use of the word and an everyday use of the word.

Let’s explore the scientific definition on the next page.



Session 1

Modern Levers


Olivia, Hamza, and Cooper have volunteered to do some work for the book fair at their K-8 school. Here’s what you need to know:

The book fair coordinator has decided to display the books for younger children on a lower shelf and the books for middle school students on a higher shelf. All the books weigh the same. The lower shelf is 1 meter high and the higher shelf is 2 meters high. The books are all on the floor near the shelves. Each book weighs 10 newtons. A newton is a way to measure force. (Think of 1 newton as how much force it takes to hold an apple. It’s reasonable, then, to say that the book weighs 10 newtons, right?)

This is what the students are doing:

TURN AND TALK

Before figuring this out scientifically, who do you think is doing the most work? The least work?

Okay. Here we go with the scientific calculation!

To figure out work, you multiply force by distance.

The force needed to hold the book in this situation is 10 newtons.

The distance the book moves in this situation is either 1 or 2 meters.

Warm-up Question: If it takes 10 newtons to hold 1 book, how many newtons does it take to hold 2 books? _______

If you said 20, then you’re right!

To determine Hamza’s work, we multiply 10 newtons (the weight of one book) by 1 meter. So the amount of work Hamza did was 10. But to say he worked “10” is kind of strange: 10 what? Well, we can measure work with something called newton-meters, but most scientists call these units joules (“joolz"). So...

by lifting 10 newtons 1 meter, Hamza did 10 joules of work.

By using this system of measuring work, can you determine the joules of work Cooper and Olivia did?

Hamza is... Cooper is... Olivia is...lifting 1 book at a time and putting it on the 1 meter shelf.

lifting 1 book at a time and putting it on the 2 meter shelf.

lifting 2 books at a time and putting them on the 1 meter shelf.

Joule is a unit that measures work.

One joule (1 J) is the amount of work done to

apply one newton of force through a distance

of one meter.

J = N x m



Session 1

Exploring “Work” as a Scientific Term


You will need:

a long flat piece of wood or other rigid material (like a ruler)

a dowel (like a large marker)

a weight (like a rock with a flat side)

With these materials, you can set up a lever system like the one below. Try it!

For today’s assignment, you will be setting lever systems in three different ways.

Specifications for System #1:

Place the fulcrum at the midpoint of the ruler. Place the load (the weight) on the right end. Be ready to apply a force with your finger to the left end.

Fulcrum (pivot point)

Push down here to lift the load on the other end. Try to remember how hard you had to push to lift the load. This amount of force will serve as your baseline. That means that you’re going to be asked to compare other forces to this force later.


Speaking ScientificallySpeaking Scientifically

Session 2

The Clever Lever



Move the fulcrum so it’s much closer to the load.

Then apply force to the other end with your finger.

Did the force you applied to lift the load in System #2 feel like it was

less than the baseline?

greater than the baseline?

about the same as the baseline?

(Remember, we’re using System #1 as our baseline.)


Move the fulcrum so it’s much closer to your hand (the effort).

Then apply force to the other end with your finger.

Did the force you applied to lift the load in System #3 feel like it was

less than the baseline?

greater than the baseline?

about the same as the baseline?


Speaking Scientifically

Session 2

The Clever Lever


Now, go back to observe something different in your three lever systems. Instead of focusing on the amount of force you apply, measure the distance that the load moves when you apply the force.

As you did with force, use System #1 as your baseline. Then mark on the table whether the movement in System #2 and #3 is greater than or less than the baseline.

FORCE applied by finger

DISTANCE load traveled

System #1 baseline

> baseline

< baseline

baseline

> baseline

< baseline

System #2 baseline

> baseline

< baseline

baseline

> baseline

< baseline

System #3 baseline

> baseline

< baseline

baseline

> baseline

< baseline

People usually come up with these findings when they try out levers set up in these ways. Did you? Feel free to try it again.

TURN AND TALK

What is the pattern you observed? Does the pattern have anything to do with work (force x distance)?



Session 2

The Clever Lever


You added energy to the system when you exerted a force on one end of the lever. The work you did was pushing down on the lever’s left end. You might think that you did additional work to lift up the load on the other end of the lever.

Not really.

Huh? The machine took your work and changed it. It ended up (most of it, anyway) as potential energy related to the load’s new position.

Let’s take another look at System #1:

1. Circle the part of the system where you did the work.

2. Put a box around the part of the system where the machine did the work.



Session 2

What’s going on here?


Now let’s make an assumption that is close to true...close enough that we want to study it:

The work put into a machine is equal to the work that comes out.

So, you might think, why do we care about machines if they don’t do work for us? Well, here’s the thing: machines can take work that’s hard for us to do and make it easier by shifting it around.

For example: It’s the same amount of work to pedal up both of the ramps below. One takes more force and less distance. The other takes less force but more distance.

TURN AND TALK

Which is which? Which would you rather try? Why? Can you relate this situation to the lever systems you worked with earlier?

=

Hey! Isn’t it true that some machines do work for us? For example, a washing machine cleans clothes

and a car drives us up hills without us doing anything?

Right. But they are powered by electricity or fuel. Right now we’re

talking about simple machines that use human power only.

Work = Force x Distance

W = Fd



Session 2

Work In and Work Out


Pulley Lab

You will need:

2 pulleys

string

load

Schematic Drawing Pulley System #1

Schematic Drawing Pulley System #2

Figure out how to set up Pulley System #1 and Pulley System #2. Try moving the load up and down using the pulley. Here is how Keziah and Avenelle decided to set up the systems:

Pulley System #1 Pulley System #2

Avenelle and her friend Keziah were visiting Avenelle’s grandfather. Avenelle’s grandfather shared his old science textbook with the girls, and they were especially interested in this old illustration. Even though the text was in French, the girls could tell it said something about how pulleys can make it possible for humans to lift objects that they could not possibly lift on their own.

At school they worked with single pulleys, but the system here with two pulleys confused them. “Why bother with the extra pulley?” wondered Avenelle.

Together they investigated.


In the Lab

Session 3


1. Devise a method to pull the string a distance of 30 cm in Pulley System #1.

Measure the distance the load moved in System #1 when you pulled the string a distance of 30 cm.

Measure the distance the load moved in System #2 when you pulled the string a distance of 30 cm.

Force needed

Distance the string was pulled

Distance the load moved

Pulley System #1 less

more 30 cm

Pulley System #2 less

more30 cm

Summarize your findings:

______________________________________________________________________________________________

______________________________________________________________________________________________

______________________________________________________________________________________________

______________________________________________________________________________________________

Can you relate your finding to the scientific definition of work?

Also indicate in the chart below which pulley system required more force to pull the string. If you don’t remember, try it again.

2. Devise a method to pull the string a distance of 30 cm in Pulley System #2.


In the Lab

Session 3

Work = Force x Distance

W = Fd


One interesting way to study levers is to consider where the three important parts of a lever are situated. Remember when you made this lever?

Your lever is in a particular group of levers called first class levers.

Think about where the effort, the fulcrum, and the load are situated in the system.

The definition of a first class lever is that the fulcrum is between the effort and the load.

Use E (effort), F (fulcrum), and L (load) to label this first class lever:

Another common way that levers are used is in pairs. Pliers are an example of two levers working together. The pair of levers is still considered first class because the (check one)

effort

fulcrum

load

is in the middle of of the system.

Can you label E, F, and L in this lever system?

fulcrum loadeffort


A Closer Look at Levers

Session 4

We’re Surrounded by Levers!


The definition of a second class lever is that the load is between the effort and the fulcrum.

fulcrum

loadeffort

Second class levers also often come in pairs.

This pair of levers used as a nutcracker is considered second class because the (check one):

effort

fulcrum

load





Session 4



TURN AND TALK

Your friend just arrived at lunch after P.E. class and he’s still amazed. He’d forgotten the combination to his gym locker, and the coach said, “No problem! I’ll cut your lock right off!” Coach then got a tool from his office called a lock cutter, and within seconds snipped the heavy-duty lock off like it was a toy.

Your friend doesn’t get it. How could Coach cut the lock so easily?

The definition of a third class lever is that the effort is between the fulcrum and the load.

fulcrum

load

effort

Third class levers also often come in pairs.

This pair of levers used as tongs is considered third class because the (check one):

effort

fulcrum

load





Session 4



If you use a better machine to get more work done with less effort, is it fair to get paid more? Or should you get paid less?

There are lots of ways to think about this question. Use the scientific ideas of machines and work to help this fictional construction supervisor with her dilemma.

Crow bar removing a nail. Hammer claw removing a nail.

All of my workers have great attitudes, but here is my problem. We have thousands of nails to remove from lumber in houses we are renovating. Most of my workers use the claw end of their hammers to remove the nails, but one uses a crow bar. The worker with the crow bar has proposed that instead of paying workers by the hour, I should pay them by counting the nails they remove. I’m not sure that this is fair though. The crow bar seems to make the work easier. What

do you recommend?


Writing

Session 5

What is the fairest way to get paid?


Dear Supervisor, _______________________________________________________________________________________________

_______________________________________________________________________________________________

_______________________________________________________________________________________________

_______________________________________________________________________________________________

_______________________________________________________________________________________________

_______________________________________________________________________________________________

_______________________________________________________________________________________________

_______________________________________________________________________________________________

_______________________________________________________________________________________________

_______________________________________________________________________________________________

_______________________________________________________________________________________________

_______________________________________________________________________________________________

_______________________________________________________________________________________________

_______________________________________________________________________________________________

_______________________________________________________________________________________________

_______________________________________________________________________________________________

_______________________________________________________________________________________________

_______________________________________________________________________________________________

_______________________________________________________________________________________________

_______________________________________________________________________________________________

_______________________________________________________________________________________________

_______________________________________________________________________________________________

_______________________________________________________________________________________________

_______________________________________________________________________________________________

_______________________________________________________________________________________________

_______________________________________________________________________________________________

_______________________________________________________________________________________________

Write a letter to the construction supervisor explaining your recommendation for how she should handle her dilemma. Use scientific ideas, focus words, and reasoning to back up your ideas.


Writing

Session 5

What is the fairest way to get paid?


Take a look at these three focus words:

machine

lever

force

A few harmless nouns, right? Useful even. Able to get the job done under the right circumstances, yes?

Well, that’s not the whole story. Turn these nouns into verbs and their more sinister sides emerge! Machine becomes the verb machinate, which means “to plan or plot, especially to do harm.” Lever transforms into leverage, which, as a verb, means “to use for gain; to exploit.” And force? Its verb definition is “to make someone do something against their will.”

How do you use these words in a sentence? Check out these examples:

The inmate machinated a way to blackmail the governor from within the prison walls.

He plans to shamelessly leverage his family’s reputation in the community to get a job that he doesn’t deserve.

“Please don’t force me!” Jonny begged. “You know that I hate spiders!”

Now it’s your turn to give the words a try. How? In the opening of a horror story, of course! Use the verbs machinate, leverage, and force to write the beginning of your own tale of treachery…

______________________________________________________________________________________________

______________________________________________________________________________________________

______________________________________________________________________________________________

______________________________________________________________________________________________

______________________________________________________________________________________________

______________________________________________________________________________________________

Sometimes a word can serve as a verb or noun but be spelled exactly the same way in each sentence. Consider these two sentences:

1. It is time to load the truck.

2. I helped remove the load from the truck.

Which one of these “loads” is a verb? Which one is a noun?

Develop your own sentence pairs that demonstrate how the words “force” and “work” can each be used as both a noun and a verb.

Force

1. _____________________________________

_____________________________________

2. _____________________________________

_____________________________________

Work

1. _____________________________________

_____________________________________

2. _____________________________________

_____________________________________


It Was a Dark and Stormy Night…

ELA



Algebraic Equations Related to Levers

Math

It’s interesting to see where and when algebraic equations show up in everyday life. Notice that the lever shown in the diagram is balancing two different masses. How can that be? Their distances from the fulcrum are also different, and they balance because the distances and the masses all relate to each other as a system! Have you ever noticed anything like this when using playground equipment, such as a see-saw?

M1 x a = M2 x bTry using the diagram to interpret this formula:

TURN AND TALK

Using the formula above, think through possible distances on each side of the fulcrum shown in this image. Could the marks on the lever be 1 cm units? 5 cm units? Either? Neither? Explain your answer.


Jared: I am so bored with this unit. Why do we need to learn about pulleys anyway? This is the 21st century. We do things electronically. These old school machines are of no interest to me at all.

Janneke: Don’t be such a dope. Pulleys are still used all over the place in the 21st century. When I was visiting my grandmother in Amsterdam last summer, we bought her a wide screen TV and they had to use a pulley on the front of the building to get it into her third-floor apartment.

Jared: Amsterdam, New York?

Janneke: No, you geographically challenged doofus. Amsterdam in The Netherlands, in Europe. I’ll show you on the map.

Jared: I don't need to see a map. But I’m still skeptical about the pulley story. Why did they use it?

Janneke: I’m not quite sure – let me email my grandmother to ask.

Janneke shows Jared the email message on her phone.

Jared: Gee, thanks, this helps a lot. It’s in some strange language.

Janneke: The language is called Dutch, and I’ll translate for you. She says, “Like you saw when you were visiting, our stairways are very narrow and steep. That’s because in the 17th century, houses were taxed based on their width on the street. So the thrifty house owners built them deep rather than wide, and there wasn’t much room for stairways. But they made the top beam in the roof long enough to stick out in front, and attached a pulley there, to use in pulling heavy loads up to higher floors.” And she doesn’t say this, but that means that they didn’t need to exert as much force as carrying stuff up the stairs would have required, either.

Jared: I still don’t believe it. That could never work. Why didn’t the wide-screen TV bump against the front of the house and get broken or break a window on the way up?

Janneke: Good question, I'll ask.

Janneke: Oh yeah, she says the houses are tilted forward, so that stuff hanging from the pulley doesn't bump.

Jared: Looks like she says more than that!

Janneke: Well, she sends a bit of criticism that I hadn’t realized it myself. But she sends you her greetings.

Jared: Well, I am still not completely convinced that pulleys are important enough machines that we should exert all this effort to study them. So what if they get used in one tiny faraway land where people were too cheap to put in proper stairs? That’s hardly justification for boring us for an entire week.

Lieve oma, mijn schoolgenoot

Jared gelooft niet dat katrollen

gebruikt worden in Nederland om

meubels te verhuizen. Kan jij

precies uitleggen hoe dat werkt

en waarom ze nodig zijn? Veel

liefs, Janneke Lieve Janneke, zoals je zag toen

je hier op bezoek was, zijn onze

trappen heel nauw en heel steil.

Dat komt doordat in de zeventiende eeuw belasting op de

huizen in de oude binnenstad

berekend werd op de breedte van

de voorgevel. Dus maakten de

zuinige huiseigenaren van die

tijd hun huizen diep in plaats

van breed, en de trappen mochten

niet zoveel ruimte in beslag

nemen. Maar zij hebben de hoogste

balk in het dak wat langer

gemaakt en daar een katrol aan

vastgemaakt, om spullen naar

boven te kunnen hijsen. Hierbij een paar fotos om het aan

je vriendje goed te laten zien

hoe het werkt. Veel liefs, ook voor je moeder,

Oma

Lieve oma, mij

n schoolgenoot

(het is

GEEN VRIENDJE)

wil weten waa

rom de

spullen niet t

egen de gevel

botsen

en stuk gaan.

Liefs, J.

Janneke, je he

bt toch gezien

dat de

voorgevels van

de oude huize

n niet

precies rechto

p staan! Van

de

hoogste verdie

ping naar de s

traat

loopt het een

beetje naar ac

hteren,

om zulke botsi

ngen en schade

precies

te vermijden.

Je moet nog ee

n keer

op bezoek kome

n en dan beter

kijken!

Groetjes aan j

e vriendje. Li

efs, Oma


Are Pulleys a Thing of the Past?

Social Studies

Setting: Jared and Janneke are studying pulleys in school, but Jared doesn’t see the practical application of these lessons.


Janneke: Jared, your stubbornness is only exceeded by your ignorance. Pulleys are used all over. Look at the cranes used to load freight onto ships. How do you think blinds get opened, or window curtains? Pulleys are used on flagpoles, on sailboats, and in aerial tramways. Without pulleys, elevators wouldn’t move up or down. And there is even a theory that pulleys were used to move huge stone blocks up to the higher levels of the ancient pyramids.

Jared: Pulleys at the pyramids? Well, that starts to sound interesting. I’m going to research that further. Tell your Oma thanks from me.

Want to help Jared with his research on pulleys at the pyramids? Check out the following websites, but read critically. You can’t believe everything you find on the web!

http://www.cheops-pyramide.ch/khufu-pyramid/rope-roll.html

http://www.haitheory.com/

http://www.dailyherald.com/article/20121218/news/712189835/

http://imaginativeworlds.com/forum/showthread.php?23290-Ezekiel-s-vision-of-ancient-Egyptian-Giza-Pyramid-construction-Four-lobe-pinion-pulley-explained&s=a27acc47c82f47ae7a89e168052e2488

Your teacher has more links!

Pulley and “tilted” house in Amsterdam


Are Pulleys a Thing of the Past?

Social Studies










Scientific or Everyday Use Definition Try using the word...

machine noun

a device that changes the magnitude or direction of a force

How is a lever a machine?

machinenoun

a device, tool, or contraption that performs a function

What machines do you use to help you do housework?

work noun

energy transferred by force acting over a distance

Work is calculated by multiplying force and distance. What unit describes work? (It starts with a “J.”)

workverb

to do a task that takes effort Do you think it’s fair for kids to be responsible for working around the house? Why or why not?

lever noun

a machine that has a rigid fixed beam and a fulcrum

How is a baseball bat a lever? How about a wheelbarrow?

leveragenoun

influence or power More outgoing students often have leverage in social situations. When might introverts have more leverage?

exert verb

to apply or put forth When you kick a ball, you exert a force upon it. What are other sports examples of exerting force?

exertionnoun

strain It takes tremendous exertion to complete a triathlon. When have you exerted yourself?

apply verb

to exert, to implement Do you apply more effort to your friendships or hobbies? Explain.

applicationnoun

a request (as in employment) What do you think is the most important part of a job application?

load noun

a weight or source of pressure How does moving the fulcrum on a lever affect the load?

loadverb

to put a significant amount of something on or in something else (like a vehicle)

Have you ever loaded a truck to help someone move?

force noun

a push or pull on an object Explain how the force of gravity is a major factor in the way our planet orbits the Sun.

forceverb

to make someone do something against their will

Have you ever been forced to choose between doing your best in school and doing your best at an after-school activity? If so, what happened?

effort noun

a force exerted by a machine (or human)

How do the locations of the effort, load, and fulcrum determine the class of lever?

effortnoun

a vigorous attempt Did you put enough effort into your schoolwork last year?

specifications noun

a description of the design and materials of a system

The specifications of how to build bombs and other illegal items are on the internet. Do you think posting such information should be illegal?

specsnoun

(short for specifications) a detailed description using measurements, such as dimensions and capacity

Websites selling electronics often show the specs of each item. Has that ever been helpful to you?


Examining the Focus Words Closely

Focus Words

SciGen Unit 8.2

work and science machines · 2019-10-20 · work and machines science activities session 1...

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