## Sunday, 26 October 2014

### Science Friction: Get a Grip

This is a simple and inexpensive experiment.  In this experiment we are learning how friction works and how it can be useful to us.

I did this experiment with my seven year old but my four year old was desperate to join in too, so she did a bit too.

All you will need are these three things...

• A force meter
• 4 different types of shoes (try keeping them all the same size)
• This free printable PDF hypothesis and results table

STEP ONE

Give your child a force meter.  Show them how it works and how we read it. Explain that force is measured in Newtons, then let them play with it for a while.

Honi loved when I mentioned that Newtons were named after Issac Newton in recognition of his work.  Honi loved the idea of having something like that named after her one day.

STEP TWO

Find four different kinds of shoes.

STEP THREE

Here is a free printable pdf of the table we used.

Fill in the table with your hypothesis - guess what force in Newtons (N) it will take before the shoe starts moving across the floor/surface it is on.

STEP FOUR

Talk about what a fair test is.  In a fair test:

• You have only one variable - that means there is only one factor we change as we do all the tests. In this experiment our variable factor is the type of shoe.
• All other conditions must remain the sameIn this test, to keep it fair, the conditions we are keeping the same is the surface the shoes are pulled along and ensure that we try to keep the force meter at a similar angle when performing the test.
You could try a laminated floor, a pavement outside, a yoga mat or a carpeted area - these are a few ideas, there are more - just remember which ever you chose you must stick with it for all the tests in this experiment.

STEP FIVE

Perform your tests -  remember to repeat the tests for each shoe 5 fives.  This is so we can use some maths to find the average if you want to continue with the follow on activities.

• Find the average! Try finding the mean, mode and median for the force of each shoe.
• Using your average make graph to of your finding.  Graphs are used to make it easier to see the results of your research, your experiment.
• Try to do the experiment again but this time choose a different surface.
• What would happen if the surface was wet? (don't do this on a carpeted surface)
• Talk about how friction is used in real life.  Discuss the materials we use for tyres and shoes.  Which shoe would you choose if it was an icy day.
• Finish of with a conclusion.  Write it down if you like. How could you improve your experiment?

What is Friction?

Friction is a force between two surfaces that are sliding, or attempting to slide, across each other it is the force between two objects that are in contact with each other.

FRICTION always slows a moving object down.

Types of friction:
1. Static friction -  The friction between two objects that are stationary (not moving).
Example: Trying to push a heavy bookcase.
2. Kinetic friction - The friction between objects where at least one object is moving.
3. Rolling friction - The friction you get when an object like a wheel or a ball, rolls on a surface.  This is sometimes known as rolling resistance or rolling drag.