Card Set Information

2011-11-20 18:22:16

buoyancy, laws and principles
Show Answers:

  1. What is the equation for pressure? Make sure to include the units that each variable is measured in.
    • Pressure = force / area
    • Pascals = Newtons / meters squared

  2. Why do some people’s ears pop when they go under water?
    When underwater you have more pressure on the outside of your ear pushing in than on the inside of your ear pushing out. Because of this your ear drum bends. This causes pain. The popping of your ear takes place when the pressure equalizes.

  3. Explain what happened to the marshmallows when we put them in the vacuum chamber.
    The marshmallows expanded in the vacuum chamber because the pump took the air out of the bell jar so the pressure inside of the air pockets of the marshmallow had greater pressure pushing out then they did pushing in so they expanded.
  4. What happened to the 55 gallon drum in the video?
    The water that is in the can boils and becomes a vapor. This water vapor pushes out the air molecules. Once all the air is out they cap the 55 gallon drum. They then throw it in ice water which causes the air vapor to condense. There is now no pressure inside pushing out so it crushes in due to atmospheric pressure.
  5. Explain why a women might put dents in a wood floor when she's walking acroos it in high-heeled shoes, but not wearing flat sandals.
    The force of the woman is the same whether she is wearing heels or flat sandals. The difference is that the area of the high heel is much less so the pressure is far greater
  6. What two variables are relalted by Boyle's Law
    • Volume and Pressure
    • V1P1=V2P2
  7. Connect Charles Law to KMT
    When the temp of a gas increases the particles start to move faster and spread out. When they move faster they are able to strike the walls of the container with more force. When the temp of a gas decreases the particles slow down and contract. Not being able to hit the walls of the container as hard or frequently.
  8. If I put a balloon in the frezzer what will happen to it?
    What gas law does this demonstrate?
    What are the two factors that will remian constant?
    • The balloon will get smaller.
    • This is Charles’ Law
    • Two variables that must stay the same are the amount of gas particles and the pressure.
  9. What happens to the pressure when the volume of a container is cut in half?
    What happens to the pressure of a container is doubled?
    • If the volume is cut in half then the pressure will double.
    • If the volume is doubled then the pressure will decrease by half.
  10. What is going to happen to the volume of the air bubbles as the scubba divers rise to the surface?
    Explain what law this is.
    • As the bubbles rise to the surface the volume will increase because the pressure will decrease.
    • This is explained by Boyle's Law
    • V1P1=V2P2

  11. What is the upward force in a fluid called?
    Buoyant Force
  12. The cause of Buoyant Force was first explained by whom?
  13. If an object floating in water has a Buoyant Force of 3 newtons, then what is the weight of the water that is displaced by the object.
    4 newtons
  14. What is neutral buoyancy?
    Neutral Buoyancy is when the weight of the object is equal to the buoyant force, the submerged object will remain at any level, like a fish.
  15. B = (Vobject)(Pfluid)(gravity)
    Calculate the buoyant force of a 3m by 2m by .5m box that is in water.
    • B = (Vobject)(Pfluid)(gravity)
    • Volume= l x w x h
    • =3 x 2 x .5
    • B= (3m3)(1g/cm2)(10m/s2)
    • =30N
  16. Who created the idea that a change in pressure in an enclosed fluid will be transmitted equally to all parts of the fluid?
    Blaise Pascal
  17. Bernoulli's principle says that as the speed of the fluid _____ the pressure exerted by the fluid _____.
    • increases
    • decreases
  18. During a hurricane do windows blow in or out? Explain why.
    They blow out because there is higher pressure inside of the house than outside the house. This is because the air is moving faster outside so the pressure is less and pressure moves from high to low causing the windows to blow out.
  19. Explain how Bernoulli's Principle explains the lift on airplane.
    As the velocity of a fluid increases, the pressure exerted by the fluid decreases. Air is a fluid. An airplane wing is shaped such that air flows at a greater velocity over its upper surface. The difference in pressure above and below the wing creates a net upward force that helps lift the plane.
  20. Explain how a hydraulic system works. Which princliple explains this? Make sure to use the pressure equation to explain your answer.
    The pressure on the small piston is transferred through the fluid to the large piston which has a larger area. Since f = pa, if the pressure is the same throughout and the area increases then the force will increase as well.
  21. The reason it is easier to pick up another person underwater than it is on land.
    Archimedes Principle
  22. The reason a balloon becomes firmer when you squeeze it.
    • Boyle's Law
    • V1P1=V2P2
  23. The idea of a hot air balloon being able to fly.
    • Charles' Law
    • V1 over T1=V2 over T2
  24. The reason why a hydraulic lift works.
    Pascal's Principle
  25. Putting your thumb over the hose to make it squirt farther is an example of what law or principle?
    • Bernoulli's Priniple
    • a special condition called Venturi effect
  26. What is the value of gravity on Earth?
    9.8 m/s2
  27. The temperature at which all particle motion stops.
    • absolute zero
    • 0 K
    • -273 oC
  28. What does the buoyant force of an object have to be in order for an object to float?
    The buoyant force has to be grater than the objects weight.
  29. Do all fluids exert the same buoyant force? Explain your answer.
    No, not all fluids exert the same buoyant force. If the fluid is more dense then there will be a greater buoyant force. If the fluid is less dense then there will be less buoyant force.
  30. Hoe does the Heimlich maneuver explain Pascal's Principle?
    The Heimlich maneuver is when you apply a sharp thrust to the abdomen of a person that is choking. The change in pressure goes through the whole system so it applies a force to the lodged item causing it to be expelled outward.