Oh, hi! With all this talk of shoes, I've been wondering how we could test a shoe to see how good it is. So I decided we'd do an experiment testing the friction of our shoes! Friction is the force that resists movement between 2 things that are touching. In other words, the friction between our shoes and the floor is what keeps us from slipping and sliding around all over the place! Here's what you'll need:

1. Shoe 2. Rubber Band 3. Tape 4. Ruler 5. Pencil and Paper for Notes

What to do:

1. Have a parent help you cut the rubber band so that it's like a string instead of a loop. Then tape or tie the rubber band to the back of your shoe.

2. Measure and write down the length from the shoe to the other end of the rubber band.

3. Slowly start pulling the rubber band straight back. Try to keep it as straight back as possible, and not diagonally up or down. As soon as the shoe starts to move, measure the new length of the rubber band and write it down in your notes.

4. Now go ahead and try it with different shoes or different types of floors. Make sure to take notes so you can keep track of your results.

What's going on?

Like I said before, one of the reasons we wear shoes in the first place is because the friction between the shoe and the floor keeps us from sliding around. It's also what made that rubber band stretch before the shoe started moving. The more friction there is, the more you'll have to pull or push that shoe to get it to move. Different types of shoes and floors will have different amounts of friction between them.

Did you notice?

Did you notice that the rubber band had to stretch more to get the shoe to start moving than it did once it was already moving? That's because there are 2 different types of friction. The friction between 2 things that aren't moving yet is called "Static Friction." The friction between 2 moving objects is called "Dynamic friction." As long as everything else stays the same, the force of static friction should be greater than the force of dynamic friction. In other words- it should be easier to pull that shoe once it's already moving.