America’s Cup Endeavour is not just about sailing. The core of the programme is the Steam curriculum — science, technology, engineering, arts and maths.

This week, we are taking a look at the letter S and learning what the students learn in relation to science when they visit either the East or West Fort.

Today’s lesson is on buoyancy. Let’s see what you will learn!

Objectives:

• Understand why an object floats or sinks.

• Understand the forces that affect an object in a liquid

• What are the characteristics of an object that floats successfully versus an object that sinks

• How can we change our object to hold or carry more load

Challenge: Create an object out of tinfoil or clay that will float in a bucket or sink.

What you need: tinfoil or clay; pennies or marbles; a bucket or sink; water.

Instructions

1. Fill up your bucket or sink with water.

2. Get hands on! Make an object out of your material that floats. HINT: Think of objects that already float, try some of those shapes out first.

3. Troubleshoot: Is your object floating? Why or why not?

4. Try again! Keep trying and testing until you get a shape that floats, then try a different shape.

5. Look and learn. What characteristics does your object have now that it didn’t when it didn’t sink (High sides, flat or curved surface, bigger object or smaller, heavier or lighter?)

6. Challenge time: see how much load your object can carry before it sinks, then challenge your family or friends to beat you.

7. Evaluate: how could you improve this challenge, let us know. We love new ideas.

Why!

There are two forces that affect how an object floats or sinks. Can you guess what they are?

If you guessed the buoyant force and density of an object you are exactly correct. The buoyant force pushes up on an object to keep it floating while its density pushes it down. Can you fill in the following sentences?

If an object’s ________ _________ is greater than its ___________ the object will float (answer: buoyant force, density)

If an object’s ______ is greater than its ____ _____ the object will sink. (answer: density, buoyant force)

So, how can we change an object (say a ball of tinfoil, or a ball of clay) to make it float? Well first we adjust its density (basically its weight distribution) by giving it a greater surface area. This also increases the object’s buoyant force.

We can also give it high sides — think cruise ship shaped. This ensures that even if an object has a greater density the water can’t get into your object.

Got cracks? A boat doesn’t float with cracks.

If you want to get really scientific, it’s based on the Archimedes principle that any object immersed or partly immersed in a fluid (i.e., a liquid or a gas) is buoyed upward by a force equal to the weight of the fluid displaced by the object.