Have you ever tried sliding on a wooden floor or an icy surface? It’s much easier to skid on a smooth surface like wood than a rough surface like carpet, this is because of friction. Friction is created when things are pulled past each other. The rougher the surface the more friction is created. Have you ever hurt your knee when sliding on carpet? This is because of the friction created between your skin and the carpet.
Imagine sliding two bits of ribbon over each other and then think how much harder it would be with two velcro strips! There’s a lot more friction with the velcro as its surface is much rougher.
First try sliding over a wooden floor with socks and bare feet. You should find it’s easier to slide with socks as there’s less friction.
Another way to investigate friction is to make a homemade friction ramp. This is just a ramp with different surfaces. The idea is to roll cars down the different parts of the ramp and investigate which surface is slowest and which is fastest.
How to make a friction ramp
A ramp – we made this one using a sheet of plywood, gaffer tape and some carpet.
Cars – LEGO/DUPLO or K’Nex
How to investigate friction
We are investigating the effect of friction on the distance travelled by a car, so the ramp surface is our variable, everything else must be kept constant.
Do not push the car, just let it go without any force behind it.
How does the surface of the ramp affect distance travelled?
Allow the car to roll down the smooth side of the ramp. Measure and record how far it travels.
Repeat using the carpet covered side of the ramp.
Which surface allows a car to travel the fastest?
Which surface slows a car down the most?
How to gather data
We repeated each test 3 times and found the average distance travelled by the cars and recorded in a table.
Friction Investigation Results
Our cars travelled a shorter distance when we used the carpet surface than when we used the smooth surface. This is because there is more friction between the car and carpet than between the car and smooth surface. The frictional forces act in the opposite direction to movement making it harder to move, therefore making the car slower and pick up less speed moving down the ramp so travelling less distance.
How is Friction helpful?
Friction between our shoes and the floor stop us from slipping and sliding around.
Friction between tyres and the road stop cars from skidding, when the road surface is icy there is less friction which makes it more likely cars will skid.
Friction between brakes and wheels help bikes and cars slow down
Ideas for younger children
Try pushing the car and comparing with the distance travelled if there is no extra force. Does the extra force make a difference?
More Friction Experiments for Kids
Another fun activity is to set up a teddy zip line investigation and test different types of harness and materials for the string.
A CD Hovercraft is great fun to make and test too.
We love this idea of investigating with a slide from Buggy and Buddy.
Or very simply, try some slipping and sliding, but be careful!
You can also find lots more forces experiments and investigations in This IS Rocket Science!
Suitable for Key Stage 2
Forces and Magnets
Compare how things move on different surfaces