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What do you already know about friction?
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Press the Right Arrow below to go to the next page.
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Press the Right Arrow below to go to the next page.
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4) Two objects are placed on a ramp. One end of the ramp is lifted.
When object A just starts to slide, the ramp looks like this:
When object B just starts to slide, the ramp looks like this:
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Press the Right Arrow below to go to the next page.
Which material had the least friction?
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Congratulations! You have finished this section.
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What if there were no friction?
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This unit explores the role of friction in everyday life. |
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Exploring the question
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Take a snapshot of your drawing when finished. |
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You have completed the introduction. Click on the UDL HOME button below.
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A Frictional Adventure
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Read the story of "Maria and Eduardo's Wonderful Summer: A Frictional Adventure" by using the forward and back buttons below. |
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Chapter 1
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"Me, too!" said Maria.
"Now children, school has only been out for a week," said their mother. "Surely you can't be bored so soon!"
"There's nothing to do," said Maria.
What do you think Sticky World and Slippery World will be like?
Do the names "Sticky World" and "Slippery World" give you any clues what those places will be like?
I predict that Slippery World will have slippery things, like ice. And Sticky World will probably be covered in sticky things, like tape.
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"Well," said their mother, "you're going to do something much better than camp! Next week you're going to visit your friend Albert. The week after that you'll stay with Jennifer."
"What's so great about Albert and Jennifer?" asked Eduardo.
"We haven't seen them since they were little kids."
"You were little kids, too, back then," reminded their mother. "You all are almost the same age. Besides it's not just Albert and Jennifer who are exciting -- it's where they live! Albert lives in Sticky World and Jennifer lives in Slippery World. Just wait till you see what that's like!"
"OK," said Eduardo, "but this better be good!"
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Chapter 2
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"Yeah," agreed Maria. "It's been doing that ever since we entered Sticky World. The motor sounds like it's working really hard, too!"
"I hope we make it!" said Eduardo.
Just then the bus driver called out, "Ladies and gentlemen, we're about to stop in Sticky World. Mind your step as you exit the bus – things are a little different here from what you're used to!"
The bus came to a sudden stop. Maria and Eduardo looked out and saw their cousin Albert and his Mom and Dad standing on the sidewalk. They waved to them. Then they got their luggage out of the rack and ran to the front of the bus to be the first ones off.
"Careful!" said the bus driver, but Eduardo and Maria weren't listening. They jumped off the bus and tried to run to their cousin, but as soon as their feet touched the pavement they stuck there.
Eduardo and Maria fell over and lay on the sidewalk, looking up at Albert who was coming to them as fast as he could.
What do you notice already that's different about Sticky World?
Do you notice anything different about the way the bus moves and sounds?
I notice that the bus is going slow and the motor sounds like it's working hard.
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There was something strange about the way Albert was moving. For one thing, he wasn't moving very fast. Also, he was picking his feet up awfully high with every step he took.
"Hi!" said Albert, when he finally got close enough to talk without yelling, "I'm glad you made it! Did you have a good trip? Here, let me help you up." Albert held out a hand to Maria and yanked her to her feet, then he did the same thing for Eduardo.
"Don't be embarrassed about falling down like that," Albert said. "Everybody does it the first time. Sticky World takes a little getting used to."
What is the force of friction like in Sticky World?
What does the story say about the force of friction in Sticky World?
The story tells me that the force of friction is greater in Sticky World.
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"What's friction?" asked Eduardo. He thought he knew the answer, but he wasn't sure.
"Friction is the force that sticks things together," answered Albert. "It's what keeps you from slipping and sliding all over the place."
"I get it," said Maria. "That's why our feet stuck to the pavement when we got off the bus."
"And we tripped!" said Eduardo.
"Right," said Albert. "Around here you have to learn to walk like this." And he showed them how to pick their feet straight up so they wouldn't get stuck.
"This stinks!" said Eduardo. He said it softly, but Albert heard him anyway.
"Oh, no, it doesn't!" He said, "Wait till you see all the neat things you can do in Sticky World!"
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Chapter 3
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They were getting sadder and sadder -- what fun could you have in a world where everything stuck together like this?
When they got to Albert's house, though, they started to change their mind. For one thing, it was a very pretty house, made of brick and two stories high with an extra room way at the top where the chimney came out. There were boxes under every window full of red and yellow flowers, and a tall oak tree in the front yard.
"That's my room," said Albert, pointing to the little room at the top. "Watch how I get to it."
Albert walked over to the house and then a surprising thing happened! Albert walked right up the wall, using his hands and feet like Spiderman! Eduardo and Maria were amazed!
Wow, the kids can all move like Spiderman!
Are there clues in the story about why the children can climb the walls like Spiderman?
To climb walls like Spiderman, there must be a greater friction force to keep the children sticking to the walls.
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In no time at all, Albert had reached the roof of the house. He walked along the wall sideways until he came to his room. Then he opened the window with one hand, holding on with the other. Then he crawled in, turned around, and reappeared at the window, smiling down at them and waving.
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"Anyone can do it," Albert called down. "Come on, you try!"
So they did. It was a little scary at first, but Maria and Eduardo found that it was really pretty easy to walk up and down walls in Sticky World. They spent the rest of the afternoon practicing, and pretty soon they were almost as good as Spiderman himself.
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Chapter 4
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"Goodbye," said Maria. "I had a wonderful time!"
"Me, too!" said Eduardo. "It's going to feel strange going back to not sticking to things."
"I can't imagine what that's like," said Albert, who had lived his whole life in Sticky World. "I'd probably fall down all the time."
"That may happen to us, too," said Maria. "Remember, we're not going home yet. We're going directly from here to our cousin Jennifer's house. She lives in Slippery World where there's practically no friction at all. I wonder what that will be like."
"Here comes your bus," said Albert's mother. "Do you have all your stuff with you? Do you have your tickets?"
Eduardo and Maria got on the bus.
"Have a good time," said Albert's mother. "I'm sure you'll find interesting things to do in Slippery World!"
How might Slippery World be different than Sticky World?
Re-read the story for clues about what is different in Slippery World.
The story says that there is almost no friction in Slippery World.
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Chapter 5
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She was trying to say something, but they couldn't hear her through the bus window.
"Watch your step!" said the bus driver, as Eduardo stepped out of the bus. "It's kind of slippery out there!"
Oops! Eduardo was careful but not careful enough. His feet slipped out from under him and he sat down rather suddenly. From the bus, the ground where he was sitting had seemed perfectly level but now that he was sitting on it he found that it sloped slightly. He started to slide downhill, going faster and faster, until he banged up against a wall and stopped.
Eduardo and Maria get hurt! Why do you think Slippery World is dangerous?
Re-read the story for clues about what makes Slippery World dangerous.
Slippery World is dangerous because the ground is not perfectly flat, so the children slid into a wall.
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"Look out, here I come!" Maria yelled. She had fallen down too and now she was sliding right at Eduardo. She slammed into the wall beside him. "Oof!" she said.
"Boy, this place is really dangerous," said Eduardo. "I wonder how Jennifer can stand it!"
"Well, you can ask her," replied Maria, "because here she comes."
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"Welcome to Slippery World!" said Jennifer. "I'm sorry you fell. There's a bit of a hill, I'm afraid. Are you hurt?"
Eduardo's arm was scraped where he had hit the wall, but he said, "No, I'm fine." Maria said, "I guess we're going to have to learn to walk all over again."
"It's not hard," said Jennifer, "you just have to dig your heel in like this and push off." And she demonstrated, gliding away just as if she were on skates.
"The thing is," she added, over her shoulder, "there isn't much friction here, so you have to pull or push on something if you want to stop or change direction." She demonstrated by digging in her heel again, making little ruts in the ground and coming to a stop.
Do you think it would be difficult to move around in Slippery World?
What does the story say about how to get around in Slippery World?
The story says that you have to pull or push on something if you want to stop or change direction.
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"It looks like this place might be fun, too," said Eduardo.
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Chapter 6
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When they tried to dig their heels in the way Jennifer had done, they would lose their balance and sit down very suddenly. And then they would keep right on sliding until they hit something. It took quite a while for them to get it right.
Finally Jennifer announced, "I think it's time for us to go home now. This street leads to my house. It dips down a bit, so you'll get going faster and faster, but don't worry. After a while it goes up and that will slow you down. Just keep both feet on the ground, don't try anything fancy, and you'll coast to my house with no effort at all."
"How far is it?" asked Eduardo.
"About three miles."
"And we can coast the whole way?"
"Sure! Sometimes we'll be going pretty fast, like down in the valley, and other times we'll go more slowly, but we'll get there. As long as you don't hit anything!"
What do the children miss about Normal World? What would you miss?
Think about Sticky World and Slippery World. Why would you want to leave them and return to Normal World?
I would want to get back to Normal World where I don't move too fast or too slow.
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"This must be what Jennifer meant when she talked about going into the 'valley,'" said Maria.
"It's not much of a valley!" said Eduardo.
"It's not much, but it's enough to get us going pretty fast, anyway!" said Maria. Indeed, she and Eduardo were going so fast that she could feel the wind in her face. She started to worry that she was going to hit a tree or something.
Just when Maria was about to try digging in her heels to slow down, the street started to slope upward and she and Eduardo started to slow down. "Whew!" said Maria. "That was scary!"
Jennifer was waiting for them at the top of this hill, standing in front of her house. She clapped her hands as they skated up to her. "That was great," she said. "You guys are really good skaters!"
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Chapter 7
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"It's been a lot of fun," said Eduardo, "and I'm really going to miss you, but..."
"I know," said Jennifer, "I'm sure you miss your Mom and Dad, too."
"It's not just that," said Maria. "There are a lot of cool things about a world with practically no friction, but I don't know..."
"It's just not the same," Eduardo said. "I mean, it's cool to be able to skate everywhere, and those slides in the park are really great, but I'm really looking forward to having my dinner plate stay where I put it."
"You know what?" said Maria, as the bus came into view, "There's just no place like home."
Press the Right Arrow below to go to the next page.
What do the children miss about Normal World? What would you miss?
Think about Sticky World and Slippery World. Why would you want to leave them and return to Normal World?
I would want to get back to Normal World where I don't move too fast or too slow.
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Congratulations! You have completed this activity. Click on the Home button below, then ask your teacher for further instructions.
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How can you measure how slippery things are?
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In this activity, you will measure the amount of friction of different surfaces. |
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Engage
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You can use the stamp on the right to help create your answer.
You can use the stamps on the right to help create your answer.
Don't forget to label the material used for your slide.
Label the slide with the material it is made from.
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Explore
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Have you ever made a ramp or slide? If so, think about the material you used and why you chose it.
You need to measure the height of the ruler when the block begins to slide.
When you type in the height, your data will be saved for you so you can compare results as you do more experiments.
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Different materials, like sandpaper and silk, feel different to the touch.
Touch the different materials. With each one, think about using that material on a slide.
Put the materials on your desk in the order of most sticky to most slippery.
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Explain
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1. What was the most sticky surface and what is your evidence?
1. What was the most sticky surface and what is your evidence?
Compare the heights needed to slide the block with different materials.
1. What was the most sticky surface and what is your evidence?
Complete the answer above.
1. What was the most sticky surface and what is your evidence?
Pick the correct answer from the choices above.
1. What was the most sticky surface and what is your evidence?
Try adding your thoughts to the correct answer above.
2. What do you think makes surfaces sticky?
2. What do you think makes surfaces sticky?
What differences do you notice between sticky and slippery surfaces?
2. What do you think makes surfaces sticky?
Examples of sticky surfaces are
They are similar because they are both
| and |
Fill in the blanks above.
2. What do you think makes surfaces sticky?
Sticky surfaces tend to be
Sticky surfaces tend to be
Pick the correct answer from the choices above.
2. What do you think makes surfaces sticky?
Try adding your thoughts to the correct answer above.
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3. What was the most slippery surface and what is your evidence?
3. What was the most slippery surface and what is your evidence?
Compare the heights needed to slide the block with different materials.
3. What was the most slippery surface and what is your evidence?
Complete the answer above.
3. What was the most slippery surface and what is your evidence?
Pick the correct answer from the choices above.
3. What was the most slipppery surface and what is your evidence?
4. What do you think makes surfaces slippery?
4. What do you think makes surfaces slippery?
What differences do you notice between sticky and slippery surfaces?
4. What do you think makes surfaces slippery?
Complete the answer above.
4. What do you think makes surfaces slippery?
Slippery surfaces tend to be
Slippery surfaces tend to be
Pick the correct answer from the choices above.
5. What do you think makes surfaces slippery?
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Elaborate
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Think back to the times you went faster or slower on the slides. What were you wearing? Remember how the different fabrics affected your speed on the slide.
You did several experiments. Think about your results. How do the results help you answer the questions?
Slides are fun! It's fun to go really fast. But sometimes you might want to go slower.
Suppose you are using your school slide and you want to slide faster. Describe what you could sit on that would help you slide faster.
Suppose you are using your school slide and you want to slide faster. Describe what you could sit on that would help you slide faster.
Think about surfaces that are slippery.
Suppose you are using your school slide and you want to slide faster. Describe what you could sit on that would help you slide faster.
Complete the answer above.
Suppose you are using your school slide and you want to slide faster. Describe what you could sit on that would help you slide faster.
Pick the best answer from the choices above.
Suppose you are using your school slide and you want to slide faster. Describe what you could sit on that would help you slide faster.
Try adding your thoughts to the correct answer above.
Why do you think that surface helps you slide faster?
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Congratulations! You have completed this activity.
What if you wanted to slide more slowly? What material could you sit on?
What if you wanted to slide more slowly? What material could you sit on?
Think about surfaces that are sticky.
What if you wanted to slide more slowly? What material could you sit on?
Complete the answer above.
What if you wanted to slide more slowly? What material could you sit on?
Pick the best answer from the choices above.
What if you wanted to slide more slowly? What material could you sit on?
Try adding your thoughts to the correct answer above.
Why do you think that surface helps you slide more slowly?
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What happens when you change the surface of a playground slide?
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In this activity, you will compare different surface materials for a slide. |
Slides are fun! Imagine if you were asked to design one. Think about the different kinds of surfaces you might use.
We will need to think about which materials would be good for a slide.
We will try out different materials in a computer model and see which makes the best slide.
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Engage
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In Sticky World, surfaces stick together. It's really hard to slide things. If you pushed something, it would stop right away.
In Slippery world, it's the opposite. Surfaces are very slippery. Things slide very easily. If you pushed something, it would just keep going.
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| In this activity, you will play with a computer model of a slide. You can change how steep the slide is. You can also change the surface of the slide. You have four choices of material: steel, wood, ice, or carpet. |
Steel:
Wood:
Ice: 
Carpet:
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What do you think? In the boxes, write down the surface
materials (steel, wood, ice, carpet) in order from the most
sticky to the most slippery.
Steel:
Wood:
Ice:
Carpet:
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Think about what each of these materials feels like. Maybe you have a steel bucket, wheelbarrow, or dog dish at home.
Each material feels different. Now you need to think about putting them in order from the most sticky to the most slippery.
Ordering the materials helps you to think about them in relationship to one another. You will then be able to design the best slide.
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Explore
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Take a snapshot of your model. Write a short description of your clicks below the snapshot.
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Take a snapshot of your model. Write a short description of your clicks below the snapshot.
You tested steel earlier. Now you'll test wood. Keep in mind that you are thinking about the amount of friction of different surfaces.
Let's test another material!
Your data is being stored in a table, so you can easily compare results.
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Take a snapshot of your model. Write a short description of your clicks below the snapshot.
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Take a snapshot of your model. Write a short description of your clicks below the snapshot.
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Explain
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1. Did the child slide on all of the surface materials?
1. Did the child slide on all of the surface materials?
1. Did the child slide on all of the surface materials?
Complete the sentence above.
1. Did the child slide on all of the surface materials?
Choose the correct answer from the choices above.
1. Did the child slide on all of the surface materials?
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2. As the results of your test, again place the slide
materials in order from the most slippery to the most sticky.
Steel:
Wood:
Ice:
Carpet:
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Elaborate
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Sometimes slides are too fast and sometimes they are too slow!
Think about a slide with peanut butter on it. Could you slide down it? What about one with jelly? Consider lots of other materials the slide could be made of.
You did several experiments using the model. How do the results help you answer the questions?
What kind of surface would keep you from moving down the slide?
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Congratulations! You have completed this activity.
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How do shoes help you walk?
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In this activity, you will explore the friction values of the bottoms of shoes. |
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Engage
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Think how the bottoms of shoes look different from one another.
Fill in the blanks in the sentence above.
Pick the correct answer from the choices above.
Try adding your thoughts to the correct answer above.
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Explore
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- force sensor
- shoes of different types
- several small bottles (about 300 ml or 12 oz) that fit into a shoe
- water
- waxed paper
- sandpaper (8"x10" sheet) - optional
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Explore
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on the right.
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| Student | Type of shoe | What it is for | What the sole is made of |
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for
a technical hint.
Be sure the force sensor is set to 10 N and not 50 N .
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You will use the force sensor to drag each shoe across the
floor. This dragging force is called the force of friction.
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Scientists use tables to record data. Keeping your data organized is very helpful when you try to make sense of it.
You need to use the data to figure out which shoe bottom has the most friction and which has the least friction.
You may own several pairs of shoes, some for sports and some for dressing up for special occasions. Think about how they feel when you walk.
Pull one of the shoes horizontally at a slow constant speed. Record the force when the speed is constant, NOT right at the beginning. Take a Snapshot of the graph and describe the type of shoe inside your Snapshot note.
Record your data in the table below. Remember to take a Snapshot of each graph and describe the type of shoe inside your Snapshot note.
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Explain
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Elaborate
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You will now have two lines on the same graph, so that you can compare them easily.
You will now have three lines on the same graph. Take a Snapshot of your graph.
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Without friction, would an object sliding on an icy lake ever stop?
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In this activity, you will explore the effect of friction on objects when you push them. |
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Engage
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Sledding on an ice-covered lake sounds fun!
Think about your own experiences on a sled or ice skates. What about rollerblades?
You need to know how friction affects sleds. You will experiment with a model of friction.
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Explore
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With this one model, we can test many different surfaces.
Watch the graph carefully each time you change the surface material
and push the box.
The graphs you made each time you pushed the box on a different
material give you important information. Think about how the graphs
are different each time.
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Explain
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You have gathered lots of facts by testing the different surfaces.
You need to interpret or make sense of your graphs to tell which material has the most friction and which has the least.
All the materials had some friction because the box stopped moving.
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Elaborate
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Using the drawing tool, draw two graphs.
First draw what you think the graph would be if the surface had lots of friction. Then, in a different color, draw what you think the graph would be if there were no friction at all. Take a snapshot of your drawing. |
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Congratulations! You have completed this activity.
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When measurements are different, what is the best value?
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In this activity you will test your skill in taking measurements. |
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Engage
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| Roll up a piece of paper the long way to make a strong solid tube. This tube will be your measuring stick. |
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Compare your results to the other groups in the class.
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Explore
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Explain
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Elaborate
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plain shoe
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aluminum foil
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Congratulations! You have completed this activity.
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Wrapping up
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What if there were no friction?
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1
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Now it's time to review and summarize what you have learned
about plants. To help, you can show all of your snapshots and
some of your written answers from the activities. They are all
in your lab book.
Review the questions on the following pages. There is a separate page for each activity that you worked on. Be prepared to share your answers with the rest of the class. |
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Maria and Eduardo's Wonderful Summer: A Frictional Adventure
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Playground surfaces
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Push it
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Slip sliding away
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Dragging shoes
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Measuring friction
In this activity, you tested your skill in taking measurements.
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Summary
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Let your teacher know that you are done. Your teacher will give you a password so you can take a short test.
| Password: |
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What have you learned about friction?
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Press the Right Arrow below to go to the next page.
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Press the Right Arrow below to go to the next page.
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When object A just starts to slide, the ramp looks like this:
When object B just starts to slide, the ramp looks like this:
Which object had more friction?
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Press the Right Arrow below to go to the next page.
Which material had the least friction?
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Now tell us what you think about this unit!
Press the Right Arrow below to go to the next page.
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Tell us what you think about this unit!
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Click the Submit button when you have finished.