Lesson 67 of 84 · Forces
Experiment⭐ 30 XP⚡ Spark LabFriction: The Force That Slows (Part 3)
Friction: The Force That Slows (Part 3).
🎯 Your mission
Predict it first. Then prove yourself right (or wrong).
⚡ The twist
The opposite of what you expect is often what happens.
Mind = Blown
🔥 A bolt of lightning is 5 times hotter than the surface of the sun.
Make a hypothesis first
Predict: what happens if you double the force?
What You'll Learn
Friction is a force that opposes motion between surfaces that touch. Rough surfaces create more friction than smooth ones. Without friction, you could not walk or grip objects.
Key Words
- inertia
- speed
- direction
Materials Needed
- toy cars
- ramps
- string
- weights
- tape
Safety First
- Be careful with scissors — ask an adult for help if needed.
Steps
Study the diagram and label the parts you recognize.
Set up a pendulum with string and a washer. Change the string length and count swings per minute for each. Graph your results.
Draw a detailed diagram of what you observe.
Write a conclusion: what did your results show? Did they match your prediction?
Check Your Understanding
Question 1
1 of 3What does friction do?
Where you see this in real life
You use this every time you flip a light switch, ride a bike, or kick a ball.
Stretch Challenge
Try this in real life this week.
Time how long a small ball rolls down something, then change the slope and try again.
For the dinner table
“Show me something at home that uses this kind of energy.”
Next Smart Experiment
We'll pick an experiment that matches exactly how you're thinking right now.
Share this experiment
Send it to a parent who's looking for a 10-minute kitchen science win.
Checkout complete lesson on Forces for 9th Grade
Get the full Forces track as a printable PDF — all lessons, worksheets, and answer keys.