1/14/11
Post date: Jan 14, 2011 2:37:59 PM
No bell ringer. Questions before the quiz?
Finish buoyancy notes
Density determines whether something will float in water or not.
Anything with a density greater than water's (1 g/mL) will sink, anything with a density less than that will float.
Bowling balls - some float, some sink
Modeling clay has a density of 1.65 g/mL -- will it float? Can you form it into a shape that floats?
Large boats float, despite the fact that the metal they are made of is much more dense than the water, because their shape makes their volume much larger and include a lot of air.
Humans vary their densities by breathing
With lungs full of air, our density is less than 1 and we float easily in water.
With empty lungs, our density is more than 1 and we sink in water.
Fish can change their density using a swim bladder
inflate swim bladder to make them less dense, so they can rise in the water
deflate swim bladder to make them more dense, so they sink in water
Submarines change their density by taking in or pumping out water from big tanks inside of them. This way, the can sink down low or rise up to the surface.
Quiz 2 - Element/Compound/Mixture, physical/chemical properties, density, buoyancy
2.3 notes - physical and chemical changes