Day 3 - Friction Action

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When two things move in contact with one another, they resist moving. No two surfaces are completely smooth -- look at something you think is smooth under a magnifying glass. Therefore, the bumps of one surface catch against the bumps in the other. The resistance that results when the surfaces rub against each other is known as friction.

The amount of friction depends on the kinds of surfaces in contact with one another and the force pressing them together. The rougher the surfaces, the greater will be the friction. The greater the weight of the objects, the greater will be the friction.

Some friction is necessary. New tires with deep, sharp treads are safer than worn-out "smooth" tires. The greater friction between the new tires and the road prevents skidding and spinning.

But too much friction wastes energy, produces unwanted heat, and wears away parts.

Objectives:

1. Students will learn that when two surfaces rub together, friction results.
2. They will learn that friction creates heat.
3. They will learn some ways that friction can be overcome.
4. Students will learn that different surfaces create more or less friction.

Introduction:

Tell the students that today they will learn about friction and how it affects some of the toys they play with. Ask them to define friction. (Friction is the resistance that results when two surfaces rub against each other.)

Materials needed:

• 5 small boxes (i.e. shoe boxes)
• 5 equal sets of rocks or other heavy objects to put in boxes
• 5 craft sticks
• 5 large rubber bands
• 25 pencils
• 5 rulers
• 5 rolls of masking tape
• 5 soup cans
• 15 Marbles
• 1 can of play dough
• 5 lids that fit over cans
• 5 tops
• 5 trays on which to spin tops
• pieces of different surfaces such as carpet, fabric, sand, wax paper, etc.