1. Archimedes’ Principle Dynamics lesson 3

2. Any body sunk in a liquid supports an upwards force where the magnitude is equal to the weight of the displaced liquid. The principle Any body sunk in a liquid supports an upwards force where the magnitude is equal to the weight of the displaced liquid. P E liquid being displaced The new force is named: BUOYANCY UPTHRUST or

3. When introducing a body in a liquid, two situations may happen: Floating or sinking P E buoyancy = weight E = P The body FLOATS PE buoyancy < weight E < P The body SINKS

4. A densities ‘affair’ Buoyancy E Body’s weight P E = m ld · g P = m b · g ld = liquid being displaced b = body floatingsinking E = PE < P m ld · g = m b · g m ld = m b  l · V ld =  b · V b V ld < V b  l >  b as m ld · g < m b · g m ld < m b  l · V ld <  b · V b  l <  b simulation

5. Eureka!! In ancient Greece, a king ordered a gold crown. He gave a mass of gold to the jeweller. The king received a golden crown that weighted exactly the same mass. The king asked Archimedes to work out if the crown was really made of gold, without damaging it. Archimedes discovered it by having a bath… How?