Air Pressure and Water Flow
Instructor Outline: Air Pressure and Water Flow
Lab length: 70-90 minutes
Lab objective: Instruct the students about pressure, suction, siphoning, hydrostatics, how straws work, and surface level equilibrium.
Materials
3 suction cups (different sizes)
Several flexible transparent tubes
2 buckets of water
1 plastic coke bottle
1 eyedropper
1 spring scale
1 plastic plate with string
1 ruler
1 calculator
Soapy water
Exploration stage: 20-30 minutes – group lab-work
The students observe the suction power of suction cups. They then quantitatively measure the pressure. The students observe equilibrium levels of fluids.
Analysis stage: 20 minutes – lecture
The instructor analyzes the findings in the exploration stage, and answers questions formed during that stage. Concept development is done on pressure and hydrostatics (pressure dependent on depth). The students can use the analysis text to follow during the lecture, read it at a later time, or use it as a reference only.
Application stage: 20-30 minutes – group lab-work
The students make some observations about equilibrium levels when one end of a tube is covered. They explore the fundamentals of siphoning, then build a Cartesian diver and have to explain the effects they observe.
Summary: 10 minutes – lecture
This is a final opportunity for questions to be addressed, and a good opportunity to explain the Cartesian diver correctly. This is time to re-iterate the core concepts and principles.
Concepts developed:
1. Air Pressure can exert extremely powerful forces, remember the large suction cup forced down simply by ambient air pressure.
2. Pressure in fluids depends only on the height of the water column, not on mass or volume.
3. Creating a pressure differential is a powerful tool (as with a siphon)
Suggested Demonstrations:
2B20.40 - Equilibrium Tubes
2B30.15 - Pop Can Collapse
2B30.30 - Magdeburg Hemispheres
2B30.u1 - Glass of Water and Card
Challenge Questions:
1. Air pressure is measured as pounds per square inch (psi) in the US (because we don’t use the metric system). Ground level air pressure on Earth is about 15 psi. The air pressure in outer space is about 0 psi. When you measure the air pressure in a tire with a blow out gauge, it tells you pressure difference, not the absolute pressure. Most tractor tires are pressurized to 12 psi. If you were to slingshot a tractor tire into outer space, what pressure would the blow-out gauge read?
................
................
In order to avoid copyright disputes, this page is only a partial summary.
To fulfill the demand for quickly locating and searching documents.
It is intelligent file search solution for home and business.