Friction: Static, Kinetic, and Useful

Lab Brief #6

🎯 Your mission

Run the experiment. Find out what really happens.

⚡ The twist

Speed isn't the same as force. Don't mix them up.

What you'll learn

Friction opposes relative sliding between surfaces. Static friction holds things in place up to a maximum; once sliding starts, kinetic friction is usually smaller. Friction is not simply a nuisance — without it you could not walk, grip or brake.

Key words

static friction
The friction that prevents surfaces starting to slide, up to a maximum value.
kinetic friction
The friction acting between surfaces already sliding past each other.

Make a hypothesis first

Guess: where does the energy go?

Say your guess out loud — then find out if you were right.

Get ready

🧰 What you need

plank
wooden block
protractor
sandpaper
cloth

Get ready

⚠️ Safety first

Support the raised end so the plank cannot slip off its rest.

Step 1 of 4 · Read

Think about what you just learned: say what "static friction" and "kinetic friction" mean in your own words before you start.

Step 2 of 4 · Do

Tilt a plank slowly with a block on it and record the angle at which sliding just begins, then the smaller angle at which sliding just continues. Repeat for three surface pairs and rank them.

Step 3 of 4 · Observe

Record what actually happened, including anything that did not match what you expected.

Step 4 of 4 · Record

Write a conclusion that answers the question this lesson opened with, and state your uncertainty.

Question 1 of 2

For most surface pairs, kinetic friction is:

How sure are you?😐 maybe

Question 2 of 2

Which task depends on friction?

How sure are you?😐 maybe

Mind = blown

⚡ Static electricity is the same physics as lightning, just smaller.

Nice work!

You got 0 of 2 right.

Next: Moments and Turning Forces All lessons

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✨ More to explore

🌍 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 it 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.”

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Friction: Static, Kinetic, and Useful

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