Slip sliding away

Discovery question

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.

Engage

Eduardo and Maria decided to invent a way to measure the friction of objects. They wanted a simple method, so that they could take their testing kit from one place to another, including Slippery World, Sticky World, and their own world. You can try out their method, which was to make a slide and see how far it needed to be tilted before an object would start sliding.

Draw a picture of a playground slide with a person ready to slide down. Different playgrounds have slides made of different types of materials. Be sure to label the type of material of the surface of your slide.
[drawing tool]

L5 Use the pencil tool to draw in the box above.* L4 Playground slide stamp L3 Playground slide stamp with separate kid stamp L2 Playground slide stamp with kid stamp L1 Playground slide with kid stamps and thought prompt

Technical Hint: How to work the Draw Tool: Small TV icon: animated GIF

Affective Network Coach - Engage & motivate - Why learn this?  Remember the last time you went down a slide. Was it fast or slow?  Can you remember what material the slide was made of?

Strategic Network Coach - Planning & performing tasks - How do I do this? How do you think you could measure the friction of different surfaces?

Recognition Network Coach- Gathering facts & describing - What is happening? I see a girl going down a slide.  I wonder if how fast she goes will have something to do with friction.

Materials

• piece of cardboard (50 cm x 10 cm)
• block of wood (10 cm x 20 cm)
• piece of sandpaper (10 cm x 20 cm)
• piece of cloth (10 cm x 20 cm)
• pieces of other materials (10 cm x 20 cm)
• ruler
• tape

Explore

1) Make a simple slide. Obtain a long piece of cardboard and a block of wood from your teacher.
2) Tape one end of the cardboard to a table.
3) Place the block of wood on the top of the cardboard slide and lift one end of the cardboard slide.
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4) Lift the slide slowly until the block of wood begins to slide.
5) On the ruler, read the height of the slide when the block of wood just starts sliding.

Technical Hint: How to set up the experiment, suggestions about taking the measurement. Lift it slowly, keep the ruler vertical, do it several times...

Height needed to start sliding = [text box] 

Explore part 2

1) Collect several materials that you can attach to your block of wood to test how slippery they are when they are placed on your slide.

2) Predict which material will start sliding at the greatest height and which will start sliding at the lowest height. Make a list below. Place them in the order of most sticky to most slippery.

Most sticky
[fill-in chart]
Most slippery
 

Affective Network Coach - Engage & motivate - Why learn this?  Different materials, like sandpaper and cloth, feel different to the touch.  I like the feel of some, but not others.

Strategic Network Coach - Planning & performing tasks - How do I do this? Touch the different materials.  With each one, think about using that material on a slide.

Recognition Network Coach- Gathering facts & describing - What is happening? Collect the materials on your desk in the order of most sticky to most slippery.

3) Now test out each material on your cardboard slide. Attach each material to the bottom of the block. Again measure the height needed to make the block slide as shown.
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4) Record that height in the table below.
Material
Height of slide
Most sticky 
Least sticky
 

Explain

1) What was the most sticky surface and what is your evidence?   [text box]

L5 currently blank L4 Compare the heights needed to slide the block with different materials. L3 I think that the most sticky surface needed the slide to be lifted  ... L2 multiple choice: I needed to lift the slide higher for the most sticky surface. I needed to lift the slide to a lower height for the most sticky surface. L1 The more slippery the surface, the less the slide needed to be lifted

2) What do you think makes surfaces sticky? [text box]

L5 currently blank L4 I think surfaces are sticky because.... L3 Examples of sticky surfaces are ...... and ..... They are similar because they are all .... L2 Sticky surfaces tend to be a)smooth b)shiny c)rough d)soft e)bumpy f)slimy L1 Besides not being shiny, sticky surfaces are also .....

3) What was the most slippery surface, and what is your evidence? [text box] 

L5 currently blank L4 Compare the heights needed to slide the block with different materials. L3 I think that the most slippery surface needed the slide to be lifted  ... L2 multiple choice: I needed to lift the slide higher for the most slippery surface. I needed to lift the slide to a lower height for the most slippery surface. L1 The more slippery the surface, the less the slide needed to be lifted

4) What do you think makes surfaces slippery? [text box]

L5 currently blank L4 I think surfaces are slippery because.... L3 Examples of slippery surfaces are ...... and ..... They are similar because they are all .... L2 Slippery surfaces tend to be a)smooth b)shiny c)rough d)soft e)bumpy f)slimy L1 Besides being shiny, slippery surfaces are ...... and ..... They are similar because they are all ....

Elaborate

1) 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.

L5 currently blank L4 Think about surfaces that are slippery. L3 I would sit on a slippery piece of ... L2 mulitple choice: I would sit on a piece of notebook paper, I would sit on a piece of wax paper L1 I would sit on anything that is slippery, like wax paper, ice, etc.

2) Why do you think that surface helps you slide faster? 

3) What if you wanted to slide more slowly? What material could you sit on?

L5 currently blank L4 Think about surfaces that are sticky. L3 I would sit on a sticky piece of ... L2 mulitple choice: I would sit on a piece of notebook paper, I would sit on a piece of sand paper L1 I would sit on anything that is sticky like sand paper, peanut butter, etc.

4) Why do you think that surface helps you slide more slowly?

Affective Network Coach - Engage & motivate - Why learn this?  Slides are fun!  Sometimes it's fun to go really fast.  But sometimes you might want to go slower.

Strategic Network Coach - Planning & performing tasks - How do I do this? 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.

Recognition Network Coach- Gathering facts & describing - What is happening? You did several experiments. Think about your results.  How do the results help you answer the questions?

Evaluate

In this activity you measured friction using the angle of a ramp. Here are some other results.
material height ramp
material A 5 cm
material B 12 cm
material C 7 cm
material D 2 cm

Which material had the most friction? (multiplechoice)
(multiplechoice)
A
B
C
D

Explain your choice.
ANSWER BOX

Which material had the least friction?
(multiplechoice)
A
B
C
D

Explain your choice.
ANSWER BOX

Suppose you were asked to design shoes for climbing an icy mountain. Describe what your design would be.
ANSWER BOX

playground_slide.jpg (image/jpeg)
slide_with_kid.jpg (image/jpeg)
Girl_ground_slide.jpg (image/jpeg)
slide_with_kid_words.jpg (image/jpeg)
slide_material.jpg (image/jpeg)
book.jpg (image/jpeg)
tech_help_tv.jpg (image/jpeg)
slide.png (image/png)
kid.png (image/png)
bubble.png (image/png)

Let's think about the material of the slide vs. of your pants.  Can we be consistent? We could add an extension about the slide and pants materials -- both being slippery or sticky, for instance? Posted by cmcintyre at Sep 07, 2007 10:11

Change second image so that there's cloth or sandpaper (some material) stuck to the bottom of the block. Posted by cmcintyre at Sep 07, 2007 12:50