Five tons of rock

How does this exhibit work?

Spinning this five-tonne rock with one finger? You can, hang in there!

What is the science behind it?

At first, the rock doesn't seem to move, but if you keep pushing it, it starts spinning.

It was not easy. This has everything to do with Newton's 1st law: an object at rest remains at rest unless a force is applied to it. And the heavier something is, the more force you have to apply.

Yet you manage! We did help you a bit by making the rock turn on a well-lubricated axis. Which has almost no friction.

Newton's 1st law in the car

Similarly, an object in motion remains in motion unless a force is applied to it. You notice that in the car.

When you ride along in the car, both your body and the car are in motion. If the car then suddenly stops, the brakes work a force on the car to bring it to a halt. Your body, however, keeps moving. That's why you move forward. Fortunately, the belt is there to keep you in place.