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Sink or swim?. The buoyancy and stability of ships. Session outline. Archimedes in practice – The science behind buoyancy (floating) Why ships need to float! – the value of shipping How do ships need to float? – A bit about moments and stability of ships. Archimedes Principle.
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Sink or swim? The buoyancy and stability of ships
Session outline Archimedes in practice – The science behind buoyancy (floating) Why ships need to float! – the value of shipping How do ships need to float? – A bit about moments and stability of ships
Archimedes Principle “An object in a fluid experiences an upward force equal to the weight of the fluid displaced bythe object”
Hull Ball Archimedes in practice: Explains why steel ships float! Ball: displaced water weighs less than the ball - SINKS Hull: displaced water weight is the same as the hull weight – FLOATS
Archimedes in practice: Explains why steel ships float! Forces are balanced Weight Weight of ship Upthrust of water Upthrust
How do we work out if something floats?The maths behind the theory: Which variables do we need to look at? weight? volume? density? mass?
Density = Mass Volume M D V We look at its DENSITY!The maths behind the theory: Calculating mass: In g Calculating volume: (cm3) Length x Height x Width h Golden Rule: If something has a density of <1g/cm3 it will float in water! w l
Did you know? British shipping earns the UK economy £162 per second!* *SeaVision UK The Benefits:Shipping in our everyday lives Employs 250,000 in the UK Generates £37 billion to UK economy per year The fishing industry provides us with a good source of protein for our diets Cargo shipping provides us with 95% of the products we use on a day-to-day basis
But we need ships not just to float……but to float upright (stability) Is this ship floating???
Just a moment… Moment Applied Centres of gravity and buoyancy when ship is upright New centre of buoyancy when ship rolls
All or nothing! OR The ship rights itself, ‘bouncing back’ from the moment applied The ship capsizes!
What influences an object to right or capsize? Centre of BUOYANCY Needs to be central and low Centre of GRAVITY Needs to be central and medium height
Practical time! Sink or swim? The Scenario Captain Eco. can’t work out what to base his new super ship design on! He has provided you with a range of materials and objects to test for stability and buoyancy See if you can give Captain Eco a hand to recommend which material/object would be the best choice for a perfectly stable and buoyant ship! Good luck. Captain Eco. is counting on you