Static Fluids AP Physics 2

i-Lab 1: Pressure What is pressure? How can you determine the weight of car by measuring the tire pressure? Discuss in your group, what data you would need to collect to determine the car’s weight.

Vocabulary Mass Volume Matter Fluid Pressure Torr Static Buoyancy Buoyant force Trajectory QUIZ ON MONDAY

Multiple Choice Question Practice . Textbook: Questions 1 – 37 Work through these questions you work through the chapter. Briefly explain why you chose each answer. Due the day of the test. I’ll give you answers to check before the test.

i-Lab 2: Will it Float? There are 6 objects and a 100 ml graduated cylinder. Determine the mass of each object using an electronic balance. Describe, step-by-step, how you will use the graduated cylinder to determine the volume of each object.

i-Lab 2: Will it Float? Which objects floated? Is there a correlation between the density of the object and whether or not it floated? If so, make a rule that describes that relationship.

i-Lab 2: Will it Float? Guiding Questions: Given your “rule” explain… why oil slicks form on the surface of water. helium balloons float, while air filled balloons sink. Ice (solid water) floats in water.

i-Lab 3: Pascal’s First Law Fill the bottle with water to the top. Leave off the lid. Remove the pins from all the lower positions. Describe the liquid streams. What shape is the stream? Why is it that shape? Are they different or the same? Why are they the same or different? Try it again with the lid screwed back on. Does it make a difference? Explain.

Pascal’s First Law We observe ... Because … So that …

Pascal’s First Law We observe that an increase in the pressure of a static, enclosed fluid at one place in a fluid causes a uniform increase in the pressure throughout the fluid. Because … So that …

Pascal’s First Law We observe that an increase in the pressure of a static, enclosed fluid at one place in a fluid causes a uniform increase in the pressure throughout the fluid. Because an increase in the pressure at one area causes more and stronger collisions of the molecules within the fluid – both on the walls of the container and on each other. So that …

Pascal’s First Law We observe that an increase in the pressure of a static, enclosed fluid at one place in a fluid causes a uniform increase in the pressure throughout the fluid. Because an increase in the pressure at one area causes more and stronger collisions of the molecules within the fluid – both on the walls of the container and on each other. So that the force applied to the piston of a hydraulic device transfers that pressure to another area, such as a hydraulic press, lift, or brake.

Pascal’s First Law P1 = P2 When: P1 = F1/A1 P2 = F2/A2 The pressures remain the same, because while the force increases, the area increases proportionally.

Pascal’s First Law Clarifying Questions: When a balloon is squeezed, why does it bulge out at another point? What happens when you press on the brake peddle of your car? Why does air in your brake line cause your brakes to not work correctly?

i-Lab 4: Pascal’s Second Law Fill the bottle with water to the top. Leave off the lid. Remove the pins from the lowest position. Then the next position upward, and then the top position. Describe the liquid streams. What shape is the stream? Why is it that shape? Are they different? The same? Why are they the same or different? Try it again with the lid screwed back on. Does it make a difference? Explain.

Pascal’s Second Law We observe ... Because … So that …

Pascal’s Second Law We observe that the trajectory of a stream of fluid coming through a hole in a container varies with the depth of the fluid. With the upper stream having less trajectory that the lower stream. Because So that

Pascal’s Second Law We observe that the trajectory of a stream of fluid coming through a hole in a container varies with the depth of the fluid. With the upper stream having less trajectory that the lower stream. Because the force exerted on the fluid pushing it through the hole comes from the weight of the fluid above the point in question. The lower hole has a greater force because there is more fluid, thus more weight, or force, acting on it. This can be calculated based on the equation: P2 = P1 + rf (y2 - y1) g So that

Pascal’s Second Law We observe that the trajectory of a stream of fluid coming through a hole in a container varies with the depth of the fluid. With the upper stream having less trajectory that the lower stream. Because the force exerted on the fluid pushing it through the hole comes from the weight of the fluid above the point in question. The lower hole has a greater force because there is more fluid, thus more weight, or force, acting on it. This can be calculated based on the equation: P2 = P1 + rf (y2 - y1) g So that the pressure on a submerged object increases with depth and the stresses near the bottom of a fluid container are greater than near the top. Give other examples of how this applies to the “real world”.

Torricelli’s Barometer The pressure of the atmosphere is equal to the pressure of the column of mercury, mmHg = Torr 1 atm = 760 Torr = 29.92 in Hg

Pascal’s Second Law Fifth Grade Questions: Scuba divers are limited in how deep they can dive. Why? Why do your ears “pop” when you go up in an airplane or into the mountains? How does a drinking straw work? How is a person living in the earth’s atmosphere similar to a fish living in the ocean?

Pascal’s Paradox Explain “Pascal’s Paradox”

The Pressure is determined by the height, not volume. Pascal’s Paradox The Pressure is determined by the height, not volume.

Problem Set A Text pp. 384-386: 17, 21, 22, 26, 27, 28, 29, 31, 38, 45 For each problem describe the solution verbally, diagrammatically, where appropriate, mathematically. Due Friday.

i-Lab: Archimedes’ Principle Part 1: Observe the demo of the cans. Explain why that happens. Part 2: Place the plastic container into the water. Record the depth it sinks to. Determine and record the mass of the object. Add masses (two at a time), repeating the process until the object floats at the surface level. Explain what you observed. Write a “rule” that can be applied to any fluid, not just water.

Archimedes’ Principle We observe…. Because…. So that….

Archimedes’ Principle We observe (write Archimedes principle) Because (explain this in terms of buoyant force; include the equation) So that (give “real world” examples and applications) Fifth Grade Questions (think of three or more questions that this principle would explain and put them in question form. Then answer the question, taking care to include the applicable physics.)

Archimedes’ Principle We observe a stationary fluid exerts an upward force on an object that is totally or partially submerged in the fluid. Because the upward, or buoyant, force is equal to the weight of the fluid displaced by the object. When the weight of the object is equal to or less than the buoyant force, the object floats. The magnitude of the buoyant force can be determined by : Ffluid = rfluid Vfluid g So that….

Archimedes’ Principle In the second i-Lab that you did, you made a “rule” about how the ability to float related to density. Now, using Archimedes’ Principle, explain why that is. READ: Section 10.7

Set B Problem Set B: pp. 383 – 388 Problems – 46, 47, 48, 50, 54, 55, 56, 60, 62, 73, 75, 79. Due Tuesday. Also, for practice do 101-105.

M/C Answers C E A D B

i-Lab: Buoyant Force Measure the cylinder thingy to determine its volume. Calculate the buoyant force that will act on the mass when submerged in the water. Measure the weight of the mass in air. Calculate to predict the weight of the mass in water. Measure the weight if the mass in water and then calculate the percent error between the theoretical and experiment measurements.