Let's Balance an Aluminium Can at a 45 Degree Angle

Let’s take a break and watch this cool magic trick that can be done with just a normal aluminium can. It's not even magic, it's actually physics!

Want to try this amazing trick yourself? What you need is just an aluminium can, a measuring cup and a small amount of water. Here’s how in 4 easy steps:  

Step 1:

- Get an empty aluminium can.

Step 2:

- Fill a measuring cup to 100ml (or just about half-fill a regular glass with water)

Step 3:

- Pour the water into the can

Step 4:

- Tilt it and balance the aluminium can at a 45 degree angle 

The key to balancing the aluminium can is making sure that the centre of gravity is supported. When the can is empty, the centre of gravity is somewhere in the centre of the can. That means when you tilt it to 45 degree angle, the centre of gravity still remains in the centre of the can but as the can is no longer upright, it will fall over. However, when the can has a little bit of water in it, the centre of gravity will be somewhat in the centre of wherever most of the water is. So when the can with water is at a 45 degree angle, the centre of gravity shifts enough to remain in the ‘centre’ of the tilted can and therefore allowing it to stay in balance.

Try this at home. Test a can with no liquid in it, and then try to figure out how much liquid is needed to balance a tin can at a 45 degree angle. Different types of cans may need different amounts of water in it to make it balance!

This blog-post is from Jiun Hong Lim, a member of the 2014 Petrosains Science Action Team (SAT) and is one of a series of blog-posts by SAT members to share and communicate science with the general public.