#lhl #lighthouselab #floatingandsinking #buoyancy #ngscience #floatandsink
Will an object float or sink when placed in water? Let's find out!
You can test the buoyancy of an object by placing it in water. Some objects stay on top, or float, when placed in water. Other objects fall to the bottom, or sink, when placed in water.

Density and buoyancy:
The amount of mass that fits into a given volume is called density. The brick is more dense than the sponge. Density is measured in grams per cubic centimeter (g/cm3). When we know the volume and mass of an object, we can calculate its density by dividing its mass by its volume. Different types of matter have different densities.

Objects that are less dense than the liquid or gas they are placed in, will float. Helium is less dense than air. That is why helium balloons float in the air. Ice is less dense than water. This is why ice blocks in your cold drink and icebergs in the ocean float. Metals are much more dense than water. However, many boats and ships are constructed from metal and are able to float on water.

They are able to float because of buoyancy. Buoyancy is the upward force exerted by a liquid or gas on an object immersed within it. The size of the force is equal to the weight of the liquid or gas that the object displaces. Consider the bottom part, or hull, of a ship. Its walls are made of metal, but most of the space inside the hull is air. When the ship enters the water, its hull displaces, or pushes away, a large volume of water. The water applies an upward force to the hull. The magnitude of the force is equal to the weight of the displaced water. The weight of the water displaced is greater than the weight of the ship and so it floats.

This video lesson is produced by Blue Ring Media in association with NGScience.com – a world-class online learning resource for K-6 science. Our international curriculum covers a comprehensive range of topics and concepts to help enhance the teaching and learning of science in your classroom and at home. Create a free account today!

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The Lighthouse Lab is produced by Blue Ring Media on the Gold Coast, Australia. For media enquiries, please email us at support@ngscience.com

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