Lesson 2 of 12 · Kinematics
Experiment⭐ 30 XPSpeed Is a Ratio, Velocity Is a Vector
Kinematics.
🎯 Your mission
Run the experiment. Find out what really happens.
⚡ The twist
Nature loves to surprise the careful watcher.
Mind = Blown
🔬 The more you look, the more nature shows you.
Make a hypothesis first
Before you start: write down what you think will happen, and why.
What You'll Learn
Average speed is distance divided by time. Velocity is displacement divided by time, so it carries a direction. A car going round a roundabout at a steady 30 km/h has constant speed but changing velocity, because its direction keeps changing.
Key Words
Tap a word to see its definition.
Materials Needed
- stopwatch
- tape measure
- cones or markers
Safety First
- Keep the walking lane clear of obstacles.
Steps
Read the explanation above and note the two key terms before you start.
Time a walker over a measured 20 m in a straight line, three trials. Compute average speed for each. Then walk the same 20 m as a semicircle and compare the speed you calculate from path length with the velocity you calculate from displacement.
Record what actually happened, including anything that did not match what you expected.
Write a conclusion that answers the question this lesson opened with, and state your uncertainty.
Check Your Understanding
Question 1
1 of 2A car travels a circular track at a steady 30 km/h. Which is true?
Where you see this in real life
This shows up in your everyday life more than you'd think.
Stretch Challenge
Try this in real life this week.
Try one experiment in real life this week — even a tiny one.
For the dinner table
“What's the most surprising thing you learned today?”
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.
Ready?
Speed Is a Ratio, Velocity Is a Vector
Run the experiment. Find out what really happens.
Full screen — no distractions
Checkout complete lesson on Kinematics for 9th Grade
Get the full Kinematics track as a printable PDF — all lessons, worksheets, and answer keys.