What Types of Forces Can Hold Objects Together?

1© 2009 McREL

Investigating Static Forces in Nature:

The Mystery of the GeckoPhysical Science

Lesson 5

What Types of Forces Can Hold Objects Together?

What Types of Forces Can Hold Objects Together?

2© 2009 McREL

What Sticks?

You will be working at several stations using an assortment of materials to test and record some ways that objects adhere to a plastic transparency.

Try the suggested procedure described at each station first before exploring on your own.

What Types of Forces Can Hold Objects Together?

3© 2009 McREL

What Sticks?

Station Materials Which Objects Stick Together?

How Do They Stick

Adhesion Method

1 Magnets, Paperclips, Plastic Transparency

2 Suction Cups, Plastic Transparency

3 Fur or Wool, Balloon, and Plastic Transparency

What Types of Forces Can Hold Objects Together?

4© 2009 McREL

What Sticks?

Station Materials Which Objects Stick Together?

How Do They Stick

Adhesion Method

4 Beaker of Water, Paper Towel, Plastic Transparency

5 Washers, Velcro®, Plastic Transparency

6 Transparent Tape and Plastic Transparency

7 Additional Station

What Types of Forces Can Hold Objects Together?

5© 2009 McREL

Variables

1. Choose one of the pair of objects that stuck together during your exploration. Describe factors (variables) that affect how well those two objects stick together.

2. Describe an adhesive in your own words. What are the properties that make it work?

3. Which factors or variables are testable and which are not?

What Types of Forces Can Hold Objects Together?

6© 2009 McREL

Observations

4. Describe how you made observations in today’s lesson.

a. What senses/tools did you use?

b. What observations were at the visible scale?

c. What dominant forces did you observe?

d. What are other forces that you observed that may be at the invisible scale?

What Types of Forces Can Hold Objects Together?

7© 2009 McREL

Adhesion MethodsMethod Definition Drawing Example Gecko Y/N Why/ Why

Not?

Friction

Air Pressure

Micro-interlocking

Magnetic

Static Electricity

Capillary Wet Adhesion

Electrical

What Types of Forces Can Hold Objects Together?

8© 2009 McREL

Making Connections

1. Describe one or two ideas that you learned during this lesson.

2. How do things stick together?

3. Which of these methods can be eliminated as an explanation for why the gecko can stick to a ceiling?

4. What should we explore next?

What Types of Forces Can Hold Objects Together?

9© 2009 McREL

Flow ChartFlow Chart

2. What Do We Mean When We Speak About Surfaces in Contact?

Scale: VisibleForce: GravityTools: Eyes

3. What Are Your Ideas About Small Sizes?

Scale: Visible/InvisibleDominant Force: VariesTools: Eyes, Instruments

7. How Do We Measure Forces at the Nano Level?

1. How Can a Gecko Walk on a Ceiling?

Scale: VisibleDominant Force: GravityTools: Eye

5. What Types of Forces Can Hold Objects Together?

Scale: Visible/InvisibleDominant Force: GravityTools: Eyes and Hands

8. How Can a Gecko Walk on a Ceiling?

4. What Do We Learn When We Look More Closely?

Scale: InvisibleDominant Force:

Extremely Small, Large in Number

Tools: Special instruments (scanning tunneling microscope)

6. How MUCH Force Is Needed to Make an Object Stick? What Factors Affect the STRENGTH of Force Acting?