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Bike Shop 3-5 / Week 03 / Wednesday
3/6
Week 03 · Friction: Grip and Slip

Wednesday

Tires that grip
// The rubbing force that helps a bike go and stop
⏱ about 15 min

Wednesday: Tires That Grip

Rocket draws a bike tire in his shop notebook. It is perfectly smooth. "Shiny and fast!" he says.

Raven holds up her sneaker and turns it over. "What do you notice on the bottom?"

Rocket sees grooves and bumps. "Hmm. Why would shoes need those?"

Nova hovers near the drawing. "Think about a wet floor," she says. "What helps feet hold on?"

Friction can help

Friction is not always a problem. Often it helps us.

Friction lets your shoes hold the floor so you can walk.

It is hard to walk on a smooth, wet floor. There is less friction.

Without friction between tires and the road, vehicles could not start, stop or turn.

Tread

Tread is a pattern of grooves on a tire or a shoe sole.

Tires and shoe soles have tread to make more friction.

Tread gives a better grip on the ground.

Bike tires help the bike grip the surface it rolls on.

Sneakers help feet grip the bike pedals.

GRIP CHECK
  • Read the question.
  • Tap your answer.
Why do tires have tread?
A tire had no friction with the road. What could it not do?
Which floor is harder to walk on?
What do we call the grooves on a tire that help it grip?
WHY THIS EXERCISETread makes more friction, so the tire grips better.
StatementTrue or false?
Friction helps us walk.?
Shoe soles have grooves to make more friction.?
A smooth, wet floor makes more friction than a dry one.?
Sneakers help feet grip the pedals.?
WHY THIS EXERCISEFriction gives us grip, and tread makes more of it.
Try it
Look at the bottoms of three shoes in your home.
Which one has the deepest grooves?
Look at a bike tire too, if a grown-up says OK. Or look at a toy car tire.
Write what you see in your shop notebook.
Safety first
Look at tires only when the bike is standing still and a grown-up holds it.
Do not spin the wheels. Keep fingers out of the spokes.
Wash your hands after touching shoe soles or tires.
In your shop notebook, draw a tire tread pattern. Then design your own tread pattern.

Great gripping! Tomorrow we see how brakes use friction to slow a wheel.

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