Buoyancy What is Buoyancy What happens when you

Buoyancy

What is Buoyancy? • What happens when you jump into a pool of water (aside from getting wet. . )? • The water pushes aside (displaces) and makes room for you. • What else?

Buoyancy and Buoyant Forces When you are swimming in water, there are two forces that work against each other and affect the motion of your body. • the force of gravity is pulling you down • the water is also pushing you up with a buoyant force

Buoyancy? • The upward part of the force exerted by fluids is called buoyancy.

Bouyancy

The Story of Archimedes • In about 250 BC, the King of Syracuse, on the Island of Sicily, suspected that his goldsmith had secretly kept some of the gold metal from the royal crown and replaced it with a cheaper metal. • The king asked Archimedes, a Greek mathematician, to determine whether the crown was pure gold or if the goldsmith was a thief!

Archimedes’ • Archimedes spent a great deal of time thinking about a solution to this problem. • Rumour has it that one day while stepping into the bath he noticed that water splashed out as he stepped in. More water splashed out the more he submerged. • Immediately he jumped out of the tub and ran, forgetting about his clothes, home yelling “Eureka!” which in Greek means “I’ve found it!”

Archimedes’ Principle • Archimedes found that the crown appeared to displace less water than a pure bar of gold. • He was able to determine that since it displaced less water the crown had a lower density than gold.

Archimedes’ Principle • The buoyant force is equal to the weight of the displaced water.

• http: //www. youtube. com/watch? v=Zj 35 t 2 ys 8 s • http: //www. brainpop. com/science/motionsf orcesandtime/buoyancy/preview. weml

Archimede’s Principle This principle explains why some objects float in water and others sink.

Salt vs. Fresh water • Seawater (salt water) has a density of 1. 03 g/m. L and fresh water has a density of 1. 00 g/m. L. • Therefore, one litre of salt water weighs more than one litre of fresh water. • That is, salt water can support more weight per volume than fresh water, so it is easier to float in salt water.