13.2 Forces and Pressure in Fluids SKIP THIS SCREEN IN 2010 Opener #13 - November 19, 2009 Write in...

13.2 Forces and Pressure in Fluids

SKIP THIS SCREEN IN 2010

Opener #13 - November 19, 2009Write in complete sentences.

1. Answer Sect. 12.3 assessment questions pg. 377 #5-7.

CW: Have out homework problems (12 problems handout from Monday.)

HW: Study guide questions due on Monday...Test on ch. 12-13 on Tuesday next week.

Pizza Party Monday - $3 - need by tomorrow... along with your pizza type.


Illustrate hair dryer and ping pong ball... You have seen some of these in stores with objects flying up and rotating around but not falling off from fans, etc.

Notes to me...

Bring extra flip cameras that have video if possible to help with downloading issues...Friday - computer lab & Notes 13.2Monday - grade problems for accuracy ch. 12

- Siphon Lab & if extra time complete any part of projects...Tuesday - Egg Drop and/or review for test activityWed. - Mac Team Meeting - substitute... - Study guide questions and study guide assignment ch. 13....Thursday - Egg Drop and/or review for test activity depending on weather...Friday - Test Ch. 12-13 - full period test...MON - holidayTUE - iMovie Egg Drop project -


Opener #4 - Friday, February 5, 2010

1. Complete questions Sect. 12.3 pg. 377 #1-4. Write in sentences or show work for math question.

2. 1st block - receive new sets of notes packet to replace yesterday’s packet. You can keep section 1. We will use 2nd page as scratch paper.

3. DEMO - ping pong ball with hairdryer...4. Notes 13.2 today... including videos... Use headphones or earbuds...There is some video on today’s assignment if able to send you...5. Lab: Computer Lab review and reinforcement... Pick up computer after notes...HW: Ch. 12 force and momentum problems due on Monday! Egg Drop Tuesday and Test ch.12-13 on Friday Feb. 12...iMovie Day will be after test on Tuesday, February 16th...


MONDAY, MARCH 28, 2011 - PAP ch. 13 and REG section 3.2 fluidsOPENER #1

1. How can you predict if an object will float in a liquid? 2. Is it possible for liquids to float on liquids? Give an example or counter example.3. What does the word viscosity mean? (prior knowledge & chapter)

CW: Notes “PAP 13.1-13.2 or REG 3.2” - Fluids, pressure, Bernoulli’s Principle, etc.QUIZ next Wednesday on the small unit of study...Your group has until April 8th to have converted your iMovie into a movie and dropped in my IN BOX to not lose any points. You will need to work on this at lunch, before school, or after school in the next couple of weeks.

HW REG: pg. 84 #1 AND pg. 86 #1-9 due TOMORROW. This is the first grade of the 9 weeks. Start out with 100%! (3 incomplete assignments will be write up in my class this 9 weeks. 1 day late may count up to 1/2 credit only in my class; other teachers may not give any.)

FIELD TRIP WEDNESDAY - Others will report to Coach Bock Room in Bldg. 18.HW PAP: pg. 393 #1-9 due Tuesday AND pg. 397 #1-8 DUE FRIDAY.


How does Pascal’s principle describe the transmission of pressure through a fluid?

Transmitting Pressure in a Fluid

According to Pascal’s principle, a change in pressure at any point in a fluid is transmitted equally and unchanged in all directions throughout the fluid.

Demo: Show with Cartesian Diver Example...


Pascal’s PrincipleA. The forces exerted

against the walls of the container are equal at a given depth.

B. When squeezed, the pressure is transmitted equally throughout the fluid.



At any given depth, equal pressures act against all points on the inside of the bottle.

When the bottle is squeezed, the pressure still increases with depth. The pressure increases equally throughout the water.


Pascal’s Principle: pressure is transmitted unchanged and evenly throughout an enclosed fluid.

Pascal’s Principle explains why bubbles are always round

Pascal’s Principle also explains how a Cartesian Diver Works.

1010

QuickTime™ and a decompressor

are needed to see this picture.

Consider the following for Siphon Lab.. THIS IS A VIDEO, Don’t click to move on....

A Hydraulic Lift use Pascal’s Principle to multiply a small force in order to lift heavy objects.


How does a hydraulic system work?A hydraulic system is a device that uses pressurized fluid acting on pistons of different sizes to change a force.


In a hydraulic lift system, an increased output force is produced because a constant fluid pressure is exerted on the larger area of the output piston.

Hydraulic Systems


The truck uses hydraulic-powered struts to lift its load. The larger area of the output piston produces the increased force.



When an input force is applied to the small piston in a hydraulic system, the piston pushes against the fluid sealed in the system.

• The pressure produced by the small piston is transmitted through the fluid to the large piston.

• The pressure on both pistons is the same.

• Because the output pressure acts on a much larger area, the output force is larger.



Quick Lab - SEE ME when you get to this point for more information for the quick activity. You will need to work with person at table. Talk to me about your conclusions and continue with your notes.

ping pong balls and 2 cups taped to table facing each other about 2 in. apart - videotape students with this to use next semester/year..., masking tape

put ping pong ball inside one of the cups - get the ping pong ball to move from one cup to the other without touching the cups or touching the ping pong ball. You may not touch it with anything including hands, pencil, etc.

Try for 5-10 minutes.

Talk about any discoveries and go on with notes...


The fast-moving stream of air from the blow dryer creates a column of low-pressure air.

The table tennis ball is suspended in an area of low pressure.

DEMO: HAIRDRYER & PING PONG BALL


How is the speed of a fluid related to the pressure within the fluid?

Bernoulli’s Principle

According to Bernoulli’s principle, as the speed of a fluid increases, the pressure within the fluid decreases.

Why does the ping pong ball behave in this way?

Why does the ball stay suspended in the column of air?

The air columncreates low pressure,with high pressure outside the column.The object tends to stay within the low pressure area (sucked in), and is pushed out of the high pressure area.

TRY THIS ONE AT HOME!


Examples of Bernoulli’s Principle:

cars on road, stream (narrow & wide), shower curtain, flight...

Try this simple experiment. • A-B - 2 Sheets of paper blow between them, what

happens?

Bernoulli’s Principle - STUDENT DEMO


Examples of Bernoulli’s Principle:

cars on road, stream (narrow & wide), shower curtain, flight...

Try this simple experiment. • (C-D)

• Hold a sheet of paper by its top corners.

• Position the paper directly in front of your mouth.

• Blow over the top surface of the paper. What happens?

• The far end of the

• paper lifts upward.

Bernoulli’s Principle - STUDENT DEMO


As the air blows across the top of the paper, the pressure exerted by the air decreases.

• The motionless air below the paper exerts a greater pressure.

• The difference in pressure forces the paper upward.

Bernoulli’s Principle (c-d)

Bernoulli’s Principle: If the velocity of a fluid is high, then the pressure of that fluid is low. Conversely, if the velocity of a fluid is low, the pressure in that fluid is high.


Wings and LiftBernoulli’s principle explains the ability of birds and airplanes to fly.

• Air traveling over the top of an airplane wing moves faster than the air passing underneath. This gives it a low pressure above. Air moves slower underneath the wing giving it a high pressure.

• The pressure difference between the top and the bottom of the wing creates an upward force known as lift.



Flight is a little more complex - Let’s see a video telling us more...

You will need to click on the link below. It should start to play. Click on the diagonal opposing arrows (vectors) to go to full screen; take a few notes from video and then continue back here with the rest of your notes....

http://www.newtonsapple.tv/video.php?id=1167

http://www.newtonsapple.tv/video.php?id=1167


Air flowing over the top of the wing is diverted up and over the wing’s curved surface.



The wings of birds produce lift in much the same way as an airplane wing. Unlike airplane wings, birds can flap their wings to produce forward movement and some lift.

The downward force created by the spoiler on a race car pushes the tires down onto the road, giving the car better traction.


SKETCH - NOTES:


Spray Bottles

Pressure differences between the solution chamber and the moving stream of water draw the solution into the stream.

Bernoulli’s PrincipleSketch the following (pg. 397 in book)

The Venturi Effect states that when a fluid passesthrough a narrow channel, the velocity will increase, causing low pressure (Bernoulli’s Principle).

Rapids are caused by the Venturi Effect

Another example….

30

Assignments

30


ASSIGNMENTS FOR FRIDAY, FEBRUARY 5, 2010

Homework problems - Force & momentum problems...due MONDAY!12 ch. 12 problems handout sheet due MON - show formula and all work...

CW: Computer Lab: Video Game Questions ch.11-13... (mostly ch. 12)


Homework problems - Force & momentum problems...due MONDAY!

Go over any questions...

CW: Finish and turn in all lab reports...CW: Work on egg drop contraption and work on study guide questions ...


Go back over assessment questions from 13.1 from yesterday as well as the following questions...


Assessment Questions

1. A water balloon can explode if squeezed tightly between two hands. Just prior to exploding, at what point of the balloon is the pressure exerted by the water greatest?

a. It’s greatest at the top of the balloon (point furthest from the ground).

b. It’s greatest at the bottom of the balloon (point nearest the ground).

c. It’s greatest at the points of contact between the balloon and the two hands.

d. The pressure exerted by the water is the same at all points of the balloon.



1. A water balloon can explode if squeezed tightly between two hands. Just prior to exploding, at what point of the balloon is the pressure exerted by the water greatest?

a. It’s greatest at the top of the balloon (point furthest from the ground).

b. It’s greatest at the bottom of the balloon (point nearest the ground).

c. It’s greatest at the points of contact between the balloon and the two hands.

d. The pressure exerted by the water is the same at all points of the balloon.

ANS: A



2. A 5-N input force of a hydraulic system corresponds to a 40-N output force. If the area of the small piston is 11 cm2, what is the area of the large piston?a. 8 cmb. 255 cmc. 288 cmd. 2200 cm2



2. A 5-N input force of a hydraulic system corresponds to a 40-N output force. If the area of the small piston is 11 cm2, what is the area of the large piston?a. 8 cmb. 255 cmc. 288 cmd. 2200 cm2

ANS: C



1. According to Bernoulli’s principle, as the speed of a moving fluid increases, the pressure within the fluid increases.

TrueFalse



1. According to Bernoulli’s principle, as the speed of a moving fluid increases, the pressure within the fluid increases.

TrueFalse

ANS: F, decreases


HW: Complete the ch. 12 problems - handout and grade on Monday...

CW: Work on the Computer Lab activity and get as far as you can. As you complete a quiz and receive a score, bring your sheet to me, and I will initial; leave your screen on the score page and will observe from my computer...

:} We will try to see how that works...


IGNORE THIS SCREEN FOR 2010

Go back over assessment questions from 13.1 from yesterday as well as the following questions...

CW: Grade the problems worksheet in class.

CW: Finish and turn in all labs and work on egg drop project. Egg drop project must be finished and constructed by Friday before leaving...

Turn in Free Fall and velocity Station Lab...Turn in Pendulum LabTurn in Siphon Lab with water fluids...

HW: Study Guide questions due by Monday. Test Tuesday over ch. 12-13.

Egg Drop will be Monday and review game for test as well... weather permitting...


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13.2 Forces and Pressure in Fluids SKIP THIS SCREEN IN 2010 Opener #13 - November 19, 2009 Write in...

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