Grippy or slippy?
Why does a sliding thing slow down and stop? Meet friction, the force that makes shoes grip and ice slippery, and race a toy car over different floors.
Read
When two things rub or slide against each other, there is a force that works against the sliding. It is called friction.[3][2]
Friction slows moving things down. It can also stop things from starting to slide.[3][4]
Even things that look smooth have tiny bumps on them. When two things rub, the tiny bumps catch on each other.[3][1]
Friction is useful! It lets your shoes grip the ground so you can walk without slipping. Shoes for running, climbing and skating all have different soles.[2][4]
Ice is slippery: there is only a little friction on ice. A wet road is more slippery than a dry road, and oil makes things very slippery.[1][3]
Rub your hands together fast. They get warm! Friction turns movement into heat.[5]
Try it: Toy car on different floors
You need
- A toy car
- A low ramp (a board on two or three books)
- Different surfaces: carpet, a towel, the smooth floor, kitchen foil
- Masking tape
- Hand spans or a ruler to measure
Safety
Keep the ramp low and steady. Let the car roll, never throw it. Keep the floor clear so nobody trips.
What to do
- Make a low ramp with a board and a few books.
- Let the car roll down the ramp onto the smooth floor. Do not push it! Mark where it stops.
- Put the towel at the bottom of the ramp and let the car roll again from the same place.
- Try the carpet and the foil too, always from the same place on the ramp.
- On which surface did the car go furthest? On which did it stop quickest?
Play: Grippy or slippy?
Is there a lot of friction (grippy) or only a little (slippy)? Tap the right group.
Your best score is kept only on this device. Nothing is sent anywhere.
Quiz
Other ages: Ages 10–11 · Ages 15–16