12/4/08

Post date: Dec 04, 2008 2:27:40 PM

Bell Activity: How can you get a hose to shoot water farther?

• • Archimedes' Principle

    • All fluids exert a buoyant force upward on any object in the fluid

    • The buoyant force = the weight of the fluid whose spot the object took

  • Fluids in motion

    • Fluids speed up to go through a smaller area.

      • Ex. Rivers run faster through narrow canyons

      • Ex. Cover part of a hose opening with your thumb to make the water move faster and shoot farther

    • Viscosity

      • Viscosity is a liquid's resistance to motion (the opposite of runniness)

      • Water has low viscosity, maple syrup and honey have higher viscosity

    • Bernoulli's Principle

      • The pressure in a fluid decreases as the fluid's speed increases

        • Light objects in your car tend to fly out open windows

        • Blow over the top of a piece of paper and it lifts upward

        • Blow through a straw to balance a ping pong ball

        • Air foils (the shape of a plane wing) cause lower pressure above the wing than below, so the wing gets "sucked" upward

• How to make the best paper air plane

  • • In PAIRS, make a paper airplane using one sheet of copy paper and up to 4 inches of tape

    • Goal is to make the plane stay in the air for the longest time possible (we will have a contest!)

    • Write step-by-step directions to make your plane

    • Switch directions with another team and have them try to make your plane while you try to make theirs. Follow their directions EXACTLY as written.

    • Get and give feedback on directions, then make changes as necessary

    • Final drafts of directions are due Monday. Spelling, organization, and neatness are all part of your grade.