Everyday Life & Technology
How does friction help us brake?
A rolling wheel slows down. The Wusels discover how friction helps with braking.
The short answer
During braking, suitable surfaces rub together. Some motion energy becomes heat, and the vehicle slows down. The tyres also need grip on the ground for effective stopping.
An imagined Wusel scene
Puschel and Flauschi investigate
At the stationary bicycle, Lumi shows Puschel the brake pad. Flauschi follows how it meets the wheel rim when the lever is pulled. He marks the two touching surfaces. His picture now shows more than a lever labelled stop.
Try explaining it
What happens to some of the motion energy during braking?
Choose a), b) or c), then explain your choice.
- a)It remains unchanged as speed in the stopped wheel.
- b)It disappears without changing into another form.
- c)It is converted into heat.
Show the explanation
Correct: c): It is converted into heat.
During braking, suitable surfaces rub together. Some motion energy becomes heat, and the vehicle slows down. The tyres also need grip on the ground for effective stopping.
Word help
- friction
- An effect between touching surfaces that resists sliding between them.
Explore in more detail
Here you will find longer explanations and further details. You can explore them together.
Understand step by step
How it works – simply explained
Motion has energy
A moving bicycle has kinetic energy. Slowing it requires changing that motion.
Friction surfaces brake
Suitable brake surfaces press and rub together, changing kinetic energy into heat, among other forms. Brake parts can get hot.
Ground grip matters too
Tyres must transfer forces to the ground. Poor grip can cause sliding. A good brake does not automatically make wet or slippery ground safe.
References for this explanation: [1]