Friction: The Force That Slows (Part 3)

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

velocity
momentum
kinetic energy

Materials Needed

stopwatch
pencils
toy cars
ramps
string

Safety First

Keep small objects away from young children.
Work in a well-ventilated area when using vinegar or other strong-smelling substances.
Dispose of materials properly after the experiment.

Steps

Step 1 — Read

Study the diagram and label the parts you recognize.

Step 2 — Do

Set up a pendulum with string and a washer. Change the string length and count swings per minute for each. Graph your results.

Step 3 — Observe

Draw a detailed diagram of what you observe.

Step 4 — Record

Write a conclusion: what did your results show? Did they match your prediction?

Check Your Understanding

Question 1

1 of 3

What does friction do?