Balancing Marshmallows STEM Challenge

Have you ever wondered how balancing toys work? You can find out with this simple marshmallow balancing STEM challenge! It's a great activity for learning about gravity and centre of mass.

balancing toy for learning about gravity and centre of mass

You'll need

A bottle with a lid

5 wooden skewers

4 Marshmallows

A Carrot

Instructions

Cut a small piece of carrot and place a piece of wooden skewer about 2 inches long into the bottom. Most of the skewer should be outside the carrot.

Place the skewer on the top of the bottle, it will fall over.

Push the pointed end of two skewers into opposite sides of the carrot, and push a marshmallow onto the end of both.

Place the carrot onto the bottle. It should now balance!

Add two extra marshmallow skewers to the carrot and see if it still balances.

Experiment by moving the marshmallows up and down the skewers.

Why did this work?

At first, the carrot didn’t balance on the bottle because it was cut unevenly and had a thin skewer stuck in the bottom, making it wobbly. The carrot stays balanced when its centre of mass (the point where all the stuff in the carrot is evenly distributed) is directly above the skewer. Gravity pulls downwards, and if the centre of mass isn't lined up over the skewer in the bottom, it creates a turning force that tips the carrot over.

By adding more skewers with marshmallows around the sides of the carrot, we were able to change the centre of mass. Too far from the bottle, and the turning force caused by gravity kept tipping it over. By adjusting the skewers and marshmallows bit by bit, we brought the centre of mass back over the bottle and the skewer at the bottom, keeping the carrot balanced.

Spreading the marshmallows lower and wider on the skewer made it more stable, in the same way a wide-bottomed mug is harder to tip over.