Thursday, 5/26/11

Warm-up: 

1.  What letter comes next?  Why?

A, E, F, H, I, K, L, M, N, ___

2.  The pennies on the right are lying on a table.  How can you move just one penny and make both a row and a column of 5 pennies?

Today: 

1. Test
2. Finish Video: Einstein Revealed
3. Discussion of science at BHS.
4. Begin Einstein's Universe

Homework:

• Test Thursday.
• If you want to improve your rocket flight grade, make new rockets.  Launch them whenever you can (maybe a free block?) and  report your best time aloft to Mr. Stapleton.
• Complete take home portion of test by this Friday, 5-27.  E-mail it to Mr. S. by Friday.

Tuesday, 5/24/11

Warm-up: 

1. What five letter word does every Harvard graduate pronounce wrong?
2. There are three misteaks in thi sentence.  Can you find all of them?

Today: 

1. Video: Einstein Revealed

Homework:

• Test Thursday.
• If you want to improve your rocket flight grade, make new rockets.  Launch them whenever you can (maybe a free block?) and  report your best time aloft to Mr. Stapleton.
• Complete take home portion of test by this Friday, 5-27.  E-mail it to Mr. S. by Friday.

Friday, 5/20/11

Warm-up: 

Imagine a speedy baseball is traveling left to right in front of us.  From our perspective, the ball is rotating counter-clockwise.  Will that rotation cause the ball to drop more quickly or more slowly than if the ball were not rotating at all?  Do you know why?

Today: 

1. 2nd Rocket launch.  See bottom for current standings.
2. If you have made four legitimately different rockets, and none of them have stayed aloft for 14seconds, bring that to Mr. Stapleton's attention.

Homework:

• Study for test on Thursday 5-26.
• Complete take home portion of test (Due next Friday 5-27).

Wednesday, 5/18/11

Warm-up: Check out the rocket standings...

Today: 

1. Wrap things up (see last class, below).  Do you have questions about the test review?  About other stuff?  Here are some answers to the practice test.
2. Give credit for any completed practice tests.
3. Test wooden projectiles (if there are any)

Homework:

• Prepare for the second (and probably final) rocket launch on Friday.  If you want a guaranteed A, this launch should bring to four your total of "unique rockets created and launched in a good faith attempt to achieve a 14 second flight."  If this applies to you, be sure to bring it to Mr. Stapleton's attention.
• Study for the test.  Test on Tuesday.

Warm-up: 

Mr. Stapleton Absent today.  No Warm-Up

Today:  

1. Discuss Final Project Options
2. Clean a row of tables.
3. Work time for test review: in-class portion and Excel take-home portion
4. Extra Credit (1% on quarter grade): "whittle" a projectile that will travel with minimal drag and will stick, nose-first, in a foam target when fired horizontally a distance of 20 meters.
5. Rebuild rocket/parachute.  The next launch will be on Friday.
6. Finish/turn in the homework that was due last class.

Next Class:

• Be prepared to venture out into the rain.  Bring necessary rain gear.  We may be launching whittled projectiles that are brought in.

Homework: 

• Finish your projectile.  Bring it to next class.
• Read over the test review and be ready to ask questions next class.  The review questions and problems are indicative of the questions and problems that will appear on the upcoming test (either Friday or Tuesday, depending on weather and the rocket launch).  Completing the test review for credit is optional.
• Begin working on the Excel take-home test (described on page two of Test review)
• If your year average is not likely to be 89.5% or better, begin working on the final project.  Mr. Joppe will allow more time when he arrives.

Warm-up: 

Suppose you have built a small boat, but it has a problem.  The boat swings quickly back and forth when you paddle. 

1.  Which way does it turn when you paddle on the right?

2.  How can you fix the boat so it will "track straight," even if you paddle on one side at a time?

3.Why does your fix work?

Today:  

1. Turn-in your homework
2. Finish building rockets.
3. Take materials to alter or repair your rocket at the launch site.
4. Launch rockets and record times.
5. Clean up the field; then clean up the room.

Homework: 

Reflect on your rocket's performance.  Devise a plan for improving your rocket.  You will have work time on Monday.  The next launch day (Wednesday, 5/18) will be short, so do not expect work time.

Warm-up: 

A rocket and its parachute have a total mass of 200g.  When fully deployed, the parachute has a circular cross-sectional area with a radius of 0.4m and a C_d of 0.8.  The density of the ambient air is 1.2kg/m³.

1.  Assuming that the parachute is fully deployed, how long will it take the rocket to fall, vertically, a distance of 50 meters?

Today:  

1. Build your rocket.  All parts of the rocket must remain connected during flight.  Timing stops when the first non-water portion of your rocket hits the ground.
2. Measure your rocket's mass for use in the homework calculations.  Estimate its cross-sectional area.

Homework: 

1. Provide a reasonable value for your parachute's C_d.  Where did you find that value?
2. Estimate a reasonable estimate of your deployed parachute's cross-sectional area.  Explain how you arrived at that estimate.
3. Use your estimates from 1-3, and the mass that you obtained during class (or an estimate) to determine your rocket's terminal velocity after chute deployment.
4. Use the rocket simulator to estimate the height of your rocket and its time aloft at the moment of parachute release.  Use a rocket C_d of 0.3, and a density of air equaling 1.2kg/m³.  This involves guessing how far the rocket will fall before its parachute is fully deployed.
5. Use your previous answers to calculate your rocket's expected total time aloft.

Rocket Guidelines

Warm-up: 

You can turn a potato gun into a rocket engine by shooting it backward and letting it propel you forward.  The force of thrust will be PA.

Alternatively, you can use a fluid for your propellant, instead of potato.  If a fluid is coming out of the same pipe with the same pressure, the force of thrust is 2PA (twice the thrust from an ejected potato).  This is true whether the fluid is air or water.

1.  How is it possible that an ejected fluid can provide twice as much force as an ejected solid?  Why does fluidity matter?

2.  Why doesn't it matter whether the fluid is water or air?

In light of #2, why does the amount of water in your rocket matter?

3.  Explain why a rocket with no water (all air) will not go very high.

4.  Give two reasons why a rocket that is nearly full of water (very little air) will not go very high.

Today:  

• Check potato gun homework problems.  Check drag calculations.
• Shoot potatoes and try to achieve maximum velocity.
• Discuss rockets and parachutes.
• Get a head start on the dowel whittling challenge???

Homework: 

1. Design a rocket with a parachute and parachute deployment system.  Search the internet for ideas regarding deployment.
2. Next Class: bring materials to add a parachute and parachute deployment system to your rocket (or build an entirely new rocket).  Have a plan, so that you can finish your rocket before Thursday.  We will be rebuild rockets on Tuesday and (hopefully) launch on Thursday.

• Regarding your parachute design, you may want to consider this...  According to sources, a "real" parachute (a semi-hemispherical shape made from a number of individual "gores") has a C_d of 1.5, while a parasheet (a flat circle, used for a parachute) has a C_d of 0.75.  Using your knowledge of drag and your intended parachute design, you can estimate the terminal velocity of your rocket after the parachute is fully deployed.  Then use this rocket simulator to estimate the height at which your parachute will (hopefully) deploy, as well as your rocket's total time aloft.

Warm-up: 

1. If you throw a ball straight up into the air, will it stay in the air longer in the real world or in a vacuum?  How could you find the answer to this question?
2. We have some pneumatic potato guns that may or may not be safe.  Propose a safe way to find out if they're going to explode when we pressurize them.

Today:  

• How to determine rocket drag coefficients, using your spreadsheet.  Here's a video link for students who were gone http://www.schooltube.com/video/cf554d92fbc2d7a3083f/Drag-Coefficients-Using-Excel
• Make sure that you have turned in (e-mailed) your spreadsheet.
• Record rocket masses on the rocket drag coefficient determination data sheet.
• Intro to potato gun problems.  Problems       solutions to the practice problems.
• Shoot potato guns and measure potato velocity.  Try to maximize velocity.

Homework:    

• "More potato gun practice" problems Problems 
• Complete  rocket drag coefficient determination data sheet.  Follow the directions at the top of the sheet.  Use Excel to find the drag coefficients.  Here's how.

Warm-up: 

Today:  

• Get rockets ready for launch
• Launch Rockets

Homework: 

• Finish Excel Spreadsheet (see homework listed for last class)

Warm-up: 

If you want to model the effect of drag on a flying object, you somehow need to incorporate a change of sign into your model.  In the Y dimension, drag is negative on the way up, and it's positive on the way down.  In Excel, you can use a conditional formula in the form of "= if(_____, then ______, else _____)." 

What could you put in the blanks?

Tallest known tsunami

Today:  

• Check Homework
• Build Rockets
• Work on Excel Spreadsheet

Homework: 

• Rocket launch next class -- weather permitting. You will have a little time to finish your rocket before we go out.  The baseball field will probably be wet, and it may be raining a little; dress appropriately.
• Due next Wednesday (May 4th): (Use this template to create an Excel file that will graph the trajectory of an object that is flung in the air.  If your spreadsheet is set up correctly, it should look like the one below. Notice that Y drag starts out negative and then turns positive as soon as the velocity becomes negative.  To do that, I used a conditional formula.  A conditional formula .." = if(velocity>0,negative drag, positive drag)"  I didn't use the word "velocity;" I referred to the current velocity cell.  I didn't use the words "positive drag" and "negative drag," I put in the calculations that would give me drag, and in the case of "negative drag" put a minus sign in front of the formula.

Warm-up: 

1. Describe two fundamentally different ways to make a rocket's flight stable (no including making it spin). 
2. Explain how each method works, in terms of CM and CP.
3. List all of the factors that you think might affect the force of drag (air resistance) acting on a flying object.

Today:  

• Intro to drag equation.  Drag practice problems.
• Start building rockets.

Video showing how to do the practice problems.  If you need a copy, click the link below, under "homework."

Homework: 

• Complete drag "homework problems"

Warm-up: 

1. Have you ever thrown a hammer? 
2. Have you ever caught a hammer that somebody threw?
3. Why is it especially challenging to catch a thrown hammer?

Today:  

• Finish paper rockets (pages 1 and 2 of this file).
• Design Water Rockets.
• Answer to #13 of paper rocket activity

Homework: 

• Bring your 2-liter bottles and other necessary rocket materials to class on the Tuesday after break.

Warm-up: 

Explain how to steer a sled.

Today:  

• Return Tests
• Rocket Stability/Steering

Homework: 

• Obtain at least two clean 2-liter plastic bottles, and bring them to class.  We will be using them to create water rockets. The first goal will be to create a 2-liter rocket with the lowest possible force of drag.

Warm-up: 

1. What causes lightning? link
2. This morning -- warm front or cold front? link
3. Why does an amber filter appear amber?

Today:  

• Test.  If you are looking for stuff to help you study, see last class, below.
• Rocket Stability/Steering

Homework: 

None

Warm-up: 

1. What sort of pressure center has moved into our region -- high pressure or low pressure?
2. Suppose you have cut four wooden Ws out of plywood.  The drawings below are unfinished perspective drawings.  How can you complete each drawing so that the wooden object appears to be observed along the direction indicated by its associated arrow?
3. What's the connection to climate map drawing?
4. Why do Northern Hemisphere tornadoes rotate counter-clockwise?
5. Why is it currently a good thing for the people of Asia that the Earth rotates Eastward?

Today:  

• Wrap-up Climate/Weather Stuff.  Block 1: finish reviewing weather/climate questions and finish video.  Block 2: check and review homework.

Monday:  Test.  Then begin unit on pressure-powered projectiles traveling through the air

Homework:  Study for Monday's test. 

• Here's a video clip explaining map drawing. 
• This is a Word document with some answers to the climate/weather questions.  These answers are incomplete; I have not included drawings in this file.
• This link connects to the video of me going over all of the climate/weather questions in block II.

Warm-up: 

1. Yesterday, the weather forecast included possible thunderstorms for some areas.  Was that prediction based on an approaching warm front or an approaching cold front?
2. The diagram below shows a river that is flowing to the left.  The depth of the river is the same at all points.  At which point is the current the fastest?
3. Why does Mt. Washington have such fast winds?
4. Why don't diesel engines need a spark plug?  Why do they sometimes need glow plugs? http://auto.howstuffworks.com/diesel1.htm
5. How is diesel fuel different from gasoline?

Today:  

• Wrap-up Climate/Weather Stuff.  Block 1: discuss homework; finish video and weather/climate questions.  Block 2: check homework; complete practice map B; answer weather/climate questions; review.

Next Class:  Begin unit on pressure-powered projectiles traveling through the air

Homework: 

• Blocks 1 and 2: Study for Monday's test.  What's on the test: 1) complete a map showing the major climate features of a fictitious continent. 2) climate/weather questions 
• Block 2: Complete Weather/Climate Questions 1-14.