Uphill or downhill?

How does the exhibit work?

Put the rollers on the steel rods. One roller seems to be rolling upwards.

What is the science behind it?

The cylinder rolls downhill, but the double cone rolls uphill. How can that be?

Gotcha! Actually, they both roll downwards. Check out the centre of the spinning rollers. That’s the centre of gravity.

If you put the double cone at the bottom of the track, the distance from the centre of gravity to the ground is greater than if you put it at the top of the track. This is because the track opens in the shape of a V. The spinning roller sinks deeper and deeper, it actually rolls downwards too, although it doesn't seem to do so.

Centre of gravity for your balance

You keep your balance by making sure that your centre of gravity is above your base of support, that’s how you won’t fall over. The base of support is between your feet.

Centre of gravity for balancing

If you want to balance a basketball on one finger, you have to hold your finger under the centre of gravity. This is the middle of the ball.

Rolling up... but then a little different

Do you know what a gravity hill is? That's the name for a road that seems to be going up but is actually going down. Cars seem to roll uphill. The cause of this optical illusion is the surrounding landscape. Don't forget to put the handbrake on!