🚚 Does a heavier toy car roll farther?

My hypothesis

If I change how much weight is on the car, then how far the car rolls will ______, because ______.

🔊 You fill in the blanks. Think about whether gravity pulls a heavy car down the ramp harder, and whether a heavy car is harder to get moving. A guess is a good because: the test finds out.

Change, measure, keep the same

Scientists call the thing you change the independent variable and the thing you measure the dependent variable. The things you keep the same are the controls: if one of them changed too, you wouldn't know which change made the difference. Try each of the 4 levels 3 times.

What you need

• 🚗 A toy car
• 📚 Some books: 2, about the same thickness
• 📦 Flat cardboard: a long flat piece, about 60 cm
• 🪙 Pennies: 20
• 🩹 Masking tape, to mark lines
• 📏 A tape measure, or a long ruler
• 🩹 Tape

Steps

1. Lean the cardboard on two books to make a ramp on a hard floor.🔊
2. Put a strip of masking tape across the ramp near the top: that's your start line.🔊
3. Put the car's front wheels on the line and let go. Don't push!🔊
4. When it stops, measure from the bottom of the ramp to the front of the car.🔊
5. Write the number in your table, then do two more tries with the plain car.🔊
6. Tape a stack of 5 pennies on the middle of the car's roof, and do three tries.🔊
7. Add 5 more pennies to make 10, and do three tries.🔊
8. Add 10 more pennies to make 20, and do three tries.🔊
9. Find the mean for each weight and draw a line graph.🔊

Every step is one you can do yourself, with a grown-up nearby. Write each number down straight away, in the table below, so nothing is lost.

Your results table

From 4th grade, add the tries for each level and divide by how many there were: that's the mean, and it goes in the last column. Then draw a line graph, because the thing you change is a number that goes up.

Why it works

🔊 Gravity pulls harder on a heavier car, but a heavier car is also harder to get moving, and the two cancel out. So the car often goes about the same distance whatever you add. Small differences are normal, because wheels, axles and floors are never perfect.

Going further (7th and up): Change a second thing: run the plain car and the 20-penny car down a 1-book, 2-book and 3-book ramp, and draw a line for each car.

Board layout

This project at your grade

From 4th grade up, the table gets a mean column. See every project for 3rd grade, or print a blank results table.

What a judge will ask

• What did you change, and what did you measure? I changed how much weight is on the car and measured how far the car rolls, in cm.
• What did you keep the same, and why does that matter? I kept the same car and the same ramp, 2 books high the same, so the only difference was how much weight is on the car.
• How many times did you test it? 3 times at each of my 4 levels.
• If you did it again, what would you change or test next? I'd run the plain car and the 20-penny car down a 1-book, 2-book and 3-book ramp, and draw a line for each car.

Make it yours

Keep this project on this device and Peabody counts down to your fair day, with a plan for each day. Nothing is sent anywhere.

Try next

• 🏎️ Which floor slows a toy car the most?2nd–6th grade · 1 day of testing · free🚗 How things move · ✂️ Paper, tape and toys
• 🚗 Does a steeper ramp make a toy car go farther?2nd–6th grade · 1 day of testing · free🚗 How things move · ✂️ Paper, tape and toys