Whatever floats your boat! Floating and Sinking Whatever floats your boat!

Measuring Objects Anything considered to have matter has mass and takes up space. Mass – amount of ‘stuff’ or matter in an object. Volume – amount of space something takes up

Calculating Density To calculate mass – triple beam balance or scale Units = g or kg To calculate volume – length x width x height, or graduated cylinder. Units = cm3 or ml To calculate Density = MASS VOLUME Units = g/cm3 or g/ml

Sinking or Floating In order for something to float, it must be less dense than the fluid in which it is immersed. Density of water = 1.0 g/cm3 Example: oil and water Layering on page 425 of textbook If density is less than water it floats If density is more than water it sinks Change pg# on notes Demo: Oil and Water

Sinking If an object is more dense than the liquid, it will sink Ex: lead, steel, fishing weight, etc… Submarine can change it’s density by taking in, or pumping out water. Ex: Cartesian diver. Needs to be a class eyedropper Fill to top with water Squeeze to increase pressure and Demo: Cartesian Diver Brainpop: Submarine

Buoyancy Buoyancy is the upward force produced by a fluid that acts on an immersed object. Ex: boats floating, figure 10, p. 427 – jellyfish, turtle, and lobster A fluid exerts pressure on all surfaces of a submerged object. Since pressure increases with depth, the pressure acting on the bottom of the object is greater.

Archimedes Principle Archimedes's Principle: The buoyant force is equal to the weight of the liquid displaced. Immersion:  all or part under water. Submersion:  completely under water Demo: Clay sinks and floats Brainpop: Bouyancy

Measuring Buoyant Force and Volume of Solids To measure buoyant force – must measure weight of water displaced in Newtons. To measure volume of irregular shaped object: it is equal to volume of water displaced.

Amount of Buoyancy Buoyant force is determined by the density of the fluid and the density of the object. More dense fluid = more buoyant force Ex: salt vs. fresh water Less dense object = higher the object floats. Density also changes with heat Hot water is less dense than cold water. Hot air less dense than cold air. This is why cold air sinks, hot air rises.