A car with drive and steering: how wheels work

What the experiment shows

Motors spin the rear wheels while swivel knuckles turn the front ones. The car is built from a chassis, four wheels and six joints — just like a real one.

How to run it

1. Press “Run” and hold W — the car drives forward. On a phone, tap the on-screen keys.
2. Hold A or D to steer. S brakes and reverses.
3. Open the example in the editor and set the wheel friction to 0.1 — the car will spin its wheels as on ice.

Questions to discuss

• What pushes the car forward — the motor or the road?
• Why does a car drive and turn badly on ice?

The science

The motor spins the wheel and the wheel pushes the road backward. By Newton’s third law the road pushes the wheel forward with friction — that is what accelerates the car. With low friction the wheels slip. Turning works the same way: the sideways friction of the front wheels swings the car around.

Try it at home

Take a toy car with rubber wheels and run it over a table and over a wet tablecloth. Compare where it accelerates faster.

What to change in the editor

• Increase the chassis mass — how does the acceleration change?
• Give the motor a different key in the “Drive” panel.