1/27/11
Post date: Jan 27, 2011 5:35:54 PM
Bell Ringer: A person in water displaces 165 pounds of water. How much buoyant force will they feel?
Fluids through openings
when fluids move from a wide to a narrow opening, they have to speed up to get all the fluid through
When fluids move from a narrow to a wide opening, they slow down.
example: putting your thumb over part of a hose's opening to shoot water faster and farther
example: narrow opening at end of a squirt gun to make water shoot faster and farther
example: clear tape over most of sink opening to shoot water fast and get user wet (good April Fool's prank!)
Pressure and movement
Fluids generally move in ways that will equalize pressure differences
Fluids flow from higher pressure to lower pressure (higher pressure side is pushing them harder than the lower pressure side)
Objects in a fluid will move with the fluid according to pressure differences
example: Fire One! game (push on pumps to move plastic piece using air pressure)
example: Compressed air leaking out of a tire into the lower pressure atmosphere
example: Hiss when opening a soda due to higher pressure air (and CO2) inside bottle moving into lower pressure atmosphere.
example: ALL WEATHER is driven by differences in pressure
P.94: 1-9 due tomorrow
Planes and paper planes
For tomorrow, you MUST know how to make a paper airplane ... have someone teach you if you don't know how!