Class 22 Thursday, 10/28/21

Warm Up:  

1. How does NASA simulate weightlessness?

2. You are trying to transfer some drippy sauce across a dinner table using only a drippy spoon.  The sauce needs to go from the pot to your plate without dripping.  Touching only the spoon, how can you make this happen?

3.  What would happen if you were standing on a bathroom scale in a motionless elevator, and then the elevator suddenly began to accelerate downward at 1g?

4.  What is the source of the "butterflies in the stomach" when we fall?

 

Today:

  • Check/review homework
  • Project Overview
    • Design an air pressure-powered water rocket that will fly as high as possible while safely carrying an electronic air pressure probe.  The flight must be controlled (cross-sectional area should be constant) and vertical.
    • Fine-tune a method to collect data that will allow you to do the following:
      • Create a graph of height vs time
      • Calculate the average force of water thrust
    • Use your data and a mathematical model (spreadsheet -- here's my example -- not shared) to determine your rocket's drag coefficient.
    • Calculate (with reasonable accuracy) the number of bottles (similar to your rocket's fuselage) that would be required to launch your body to a height of 10m.  Also calculate the acceleration you would experience.
    • This will be a group project, but parts will be completed individually.
  • Begin work on the mathematical model.  You will be using this for more than just the project, so you must complete your own, individually.
    • Make a copy of this template -- Trajectory With Drag Spreadsheet Template
    • Follow these directions...
    • As you proceed, verify your formulas with these "Solutions" -- which assume that you leave the originally-provided values in the yellow cells

Homework:

Class 21.5 Wednesday, 10/27/21

Warm Up:  

How fast does chalk fall? My spreadsheet answer

Today:

  • Check/review homework

Homework:

Class 21 Tuesday, 10/26/21

Warm Up:  

A parachuter steps out of a plane.  The total mass of the parachuter and gear is 100kg.  After falling for a while, the parachuter reaches a terminal velocity of -55m/s.  A short time later, the parachuter pulls the chute cord and reaches a new terminal velocity of -3m/s.  From that point in time, the parachuter continues to drift to the ground.

Fill out the missing data in the table on packet page 15...

 

Today:

  • Check/review homework
  • Finish the notes -- graph on packet page 14
  • Work Time -- see assignment below

Homework:

Image result for cat falling from buildingClass 20.5 Monday, 10/25/21

Warm Up:  

According to this article, emergency clinic records of 132 cats that jumped from windows of buildings showed a 90% survival rate.  The average drop was 5.5 floors. 

Injuries increased with increasing heights up to 7 floors. When cats fell from over 7 floors, they actually suffered from “less injuries.” 

1. What's going on?

2. What's the rule for deciding whether to use "less" or "fewer?"  Which applies here?

3. When does a falling cat experience zero net force?

4. When is a falling cat a "free-falling" cat?

5.  When does a falling cat experience maximum net force?

 

Today:

Homework:

  • Packet p. 16 -- "Conceptual Practice With Drag"

Class 20 Friday, 10/22/21

Warm Up:  

1.  Explain how a nordic skier can ski forward on level ground with parallel skis (classic style) and without using poles.

2.  Can this be done with downhill skis?  Explain.

Today:

Homework:

  • Multibody Drill A, problems 1-6, on packet pages 11-12.

Class 19.5 Thursday, 10/21/21

Warm Up:   I have a length of treated 4"x4" lumber, some large nails, a hammer, and a large rock.  How will it feel if I put the rock on my head and then have someone pound nails into the wood on top of the rock?

Today:

Homework:

  • On page 10 of the packet, finish writing net force equations for at least two more possible systems.  We will have already finished a few.

 

Class 19 Wednesday, 10/20/21

Warm Up:   None -- retake day

Today:

  • Test retakes, work time

Homework: (continued from yesterday)

Class 18.5 Tuesday, 10/19/21

Warm Up:   On level ground, Tim begins sliding with a velocity of 6m/s.  If Tim's slide lasts for 2 seconds, what is the coefficient of kinetic friction between Tim and the slide?

Today:

  • Check/review homework
  • Work time -- not enough time today for a proper introdu ction to "multibody" problems.
  • The optional retake will be next wednesday

Coming up: 

Homework: Due on Thursday!

Class 18 Monday, 10/18/21

Warm Up:   One way to find the center of mass (a.k.a. balance point) of a stick is to support it with two hands and then slowly move those two hands together until they meet under the stick's center of mass.  Why does this method work?

Today:

  • Classroom culture check-in survey
  • Check/review homework
  • Notes:  Friction (Packet page 8) Filled-in version
  • The optional retake will be next wednesday
  • Work time -- homework or re-do shot one of the launcher project.  It will be a horizontal launch at some height.  No obstacle.

Coming up: 

Homework:

Class 17.5 Friday, 10/15/21

Warm Up:   Why can't you literally "pull yourself up by your own bootstraps?"  This question has also been stated as "why can't you pick yourself up?" 

Today:

  • Return Launcher Contest Problems
  • Check/review homework
  • Notes:  Newton's 3rd Law (Packet page 7) Filled-in notes  video of notes
  • The optional retake will be next wednesday

Homework:

Class 17 Thursday, 10/14/21

Warm Up:   It is possible to remove a sheet paper from under a dry erase pen without touching or tipping the pen.  How can one do this without tipping the pen?  Why does the pen usually fall? 

Today:

Homework:

  • Conceptual #1-2 and Problems #1-6 on pages 4-5 of the Unit 3 Packet  This solution link doesn't seem to be working, so I put the solutions in Google Classroom.  Answers and Solutions
Class 16.5 Wednesday, 10/13/21

Warm Up:   There is a heavy object suspended from the ceiling by a string.  Another segment of the same string is hanging downward from the object.  I am going to pull on the bottom string until one of the two strings breaks.  Which string is going to break first?  Why?

Today:

  • I failed to record some assignments that were due around 9/27 and 9/28.  Who did/didn't do them? (enter grades)
  • Contest Results
  • Did anyone discover any test grading mistakes?
  • Get Unit 3 Packet (Newton's Laws in 1-D)
  • The optional retake will be next wednesday.
  •  Does anyone have questions?

Homework:

  • None -- if you're planning to retake the test, use tonight to prepare.
Class 16 Tuesday, 10/12/21

Warm Up:   Get your launchers ready.  No practice shots!  Make a plan.  Once we get going, we need to achieve less than one minute per shot.  The first shooters can have a little extra time.

Today:

  • Hand in your contest problem solutions.  Make sure that all of your names are on the sheet.
  • Projectile Launcher Contest
  • Return tests.  Be aware that a few students have not finished the test.
  • Test score distribution

Homework:

  • Look over your test and see if you think there were any grading errors.  If you want clarification on a question or problem, watch the corresponding video provided in Google Classroom.  If you think there may be a grading mistake, tell me tomorrow.
Class 15.5 Thursday, 10/7/21

Warm Up:   None

Today:

  • Test, part 2 -- Projectile Problems
  • Work on the contest problems -- due next Tuesday, at the beginning of class.

Homework:

  • Solve the contest problems.  Make a plan for setting up your shots.
Class 15 Wednesday, 10/6/21

Warm Up:   None

Today:

  • Test, part 1-- Conceptual Questions and River Problems
  • Hand out the contest problems.

Homework:

  • Contest problems are due next Tuesday
Class 14.5 Tuesday, 10/5/21

Warm Up:   A boat is following a heading of 56 degrees N of E, and its speed in still water is 1.3 m/s.  Find the velocity of the river's current if the boat's actual velocity (relative to the Earth) is 3.2m/s in a direction 17 degrees W of N. Solution... Video explanation

Today:

Homework:

  • Study
  • Contest problems are due next Tuesday.  Turn in one team copy at the beginning of class and keep the other copy for your own use.
Class 14 Monday, 10/4/21

Warm Up:  Final launcher considerations...

1.  How are you going to aim your launcher in the horizontal plane?

2.  How are you going to aim your launcher in the vertical plane?

3.  How are you going to decide on your projectile's initial height? [Remember that you will be given a vertical "launch window," and it is up to you to determine the exact launch height.]

4.  How are you going to hold your launcher steady, at the height and angle of your choice?

5.  What are you going to do if you take a test shot and it turns out that your distance is off by a large amount?

Today:

Homework:

  • Test on Wednesday and Thursday
  • Do you have questions about anything on the test?  Add your question or request to this Google Doc (as early as you can -- I may not get to late submissions).  I will either create a video answering your question, or I will answer it tomorrow during class.
Class 13.5 Friday, 10/1/21

Warm Up:   Let's try out the PhET Projectile Motion Simulation and see what it has to offer.

The riverboat simulator is also interesting, but I would change the wording a bit.  Can you guess what I would change?

Today:

  • Check/review homework.
  • Final launcher practice -- set up some test shots
  • Hand out the contest problems

Other Stuff

Homework:

  • Study
Class 13 Thursday, 9/30/21

Warm Up:   What's the best way to create a graph like this one?  Exactly what do you need to do?

My spreadsheet

Today:

  • Check/review homework
  • Read over some of the details in the 2nd launcher handout.
  • Launcher calibration and practice

Homework:

Class 12.5 Wednesday, 9/29/21

Warm Up:   I like to start projectile problems by listing important variables in the X and Y dimensions (x and y components of motion).  It might also be helpful to list some resultant variables.  Let's try.

Today:

Homework:

Class 12 Tuesday, 9/28/21

Warm Up:  

1.  Based on the diagram to the right, provide definitions for precision and accuracy.  Which is easier to fix?

2.  Can you suggest some ways to improve precision?  Accuracy?

3.  What are some probable sources of error in your attempts to hit the target?

 

Today:

  • Group size limit change -- groups of 3 are now okay.  You can re-shuffle groups today.  If you want to "make a copy" of your spreadsheet and use that to create a new spreadsheet for your new group, that's okay.  However, if you were one of the group's who had a member who solved the bonus problem, we will need to discuss what makes sense in that case.
  • Get Trajectory Contest Project Handout #2  PDF Version
  • Launcher assembly, modification, data collection, and calibration graph creation.
  • Launcher Parts:    What to save in your Ziplock bag...
  • If your spreadsheet calculators don't work right now, record your calibration data anyway.  Then fix your spreadsheet and figure out the intitial velocities later.
  • Store your plunger/bands, projectile, and trigger/string in a Ziplock bag with your names and block on it.

Homework:

Class 11.5 Monday, 9/27/21

Warm Up:  

The diagram on the right shows the trajectory of a free-falling projectile that was launched horizontally.  Sketch the diagram.  Show/label the projectile's overall velocity (v), x velocity (vx), and y velocity (vy) at the start of its flight and at some other point in the flight.

Today:

  • Return retakes -- Reflect on 1st Unit, now that you've been through a full unit cycle.
  • Check/Review Homeworks
    • Projectile trajectory answers
    • Pennington practice test

Homework: Finish any homework that you didn't complete for last class (including the projectile launcher practice problems -- p. 15; and Mr. Pennington's practice test -- p. 10-15)

 

Class 11 Friday, 9/24/21

Warm Up:  

None -- test retake day

Today:

  • Retake
  • Work time -- Project stuff or Mr. Pennington's old Chapter 3 Test (page 10-14 of the Unit 2 Packet Solutions 

Homework:

Class 10.5 Thursday, 9/23/21

Warm Up:  

Find a combination of initial angle and initial speed that will carry a projectile from the launch point to the target (assuming no air resistance).

You can guess, and I will check, with my private spreadsheet. :-)

Today:

  • Clarify the homework assignments.
  • Work time.  Complete your spreadsheet and then use Sheet 1 to complete the projectile practice problems on p. 15 of the packet.
  • Test retake tomorrow.  If you're not retaking the test, you can work on Mr. Pennington's old test (p. 10-14)

Homework:

  • Use Sheet 1 of your spreadsheet (or a copy of it) to complete the Projectile Launcher Spreadsheet Practice Problems on p. 15 of the Unit 2 Packet.
  • Sheets 1 and 2 of your group's trajectory spreadsheet are due by Monday.  At least one of you should submit the spreadsheet in Google Classroom.
Class 10 Wednesday, 9/22/21

Warm Up:  

1.  Based on the existing pattern, what should number should appear in the 7th row of column C?

2.  If we wanted to continue that pattern quickly and easily, how could we set up a spreadsheet to do it?

 

Today:

  • Please answer this brief multiple choice question (for our Wednesday afternoon teacher meeting).  Thanks!
  • Check/review homework
  • Trajectory Project:
    • Get Trajectory Contest Project Handout #1 PDF Version
    • Find a partner.
    • Modify this spreadsheet template to create the Sheet 1 ("Trajectory") of your Trajectory Project spreadsheet.
    • As you build your spreadsheet, use this screenshot to check your work.  Keep the yellow cells the same as mine so that you can use my calculations to verify yours. .  I plan to make a video during class and then make the video available on my YouTube channel.
    • FYI, here are what Sheets 2 and 3 will look like...
      • Sheet 2 (Launcher Calibration)
      • Sheet 3 (Launcher Calibration Graph)

Homework:

  • Divide tasks and work on the project at home.  Before class on Monday, you should be finished with Sheet 1, as well as the initial velocity calculators on Sheet 2.  Hopefully, you will calibrate your launcher on Monday (split block) and Tuesday. 
  • Test retake on Friday. 
Class 9.5 Tuesday, 9/21/21

Warm Up:   Sketch a head-to-tail diagram for each of the following.  We will look at the graphical solutions afterward.

1.  A baggage conveyor is moving in a direction 25 degrees South of East at a rate of 1.5m/s.  A bug riding on the conveyor has a velocity of 2m/s in a direction 30 degrees East of South.  What is the bug's heading and "speed on a still conveyor?"

2. A river's 3mph current flows in a direction 15 degrees West of North.  A swimmer, whose speed in still water is 2m/s, swims across the river with a heading 35 degrees South of West.  What is the swimmer's velocity, relative to the Earth?

3.  A superhero steward on an airplane is traveling in a direction 10 degrees East of South, and their speed is 580mph.  The plane's velocity is 460mph in a direction 5 degrees West of South.  What is the steward's heading and their "speed on a still plane?"

 

Sketches and answers: ---Argh!! #1 is wrong!  But 2 and 3 are right.

 

Today:

  • Update seating chart in A8
  • For even more non-orthogonal river problem practice, see the warm-ups from last year's classes #20 and #21.  A link to a video solution is included after each warm-up.
  • Tpmorrow:  Modify this spreadsheet template to create a mathematical model of a projectile's trajectory.  Make your own copy of the template.  Then use formulas to create the spreadsheet. .  I plan to make a video during class and then make the video available on my YouTube channel.
  • Check/review homework.

 

Homework:

  • Projectile Practice Problem #3 on p. 9 of the Unit 2 Packet Solutions
  • Don't forget that your chance to retake the test is on Friday.
Class 9 Monday, 9/19/21

Warm Up:  Suppose you shoot a projectile, horizontally, from the edge of a school tabletop that is 0.95m above the floor.  If the projectile hits the floor at a distance of 14 floor tiles from the table...

a.  What is the projectile's v0?

b.  How would you find the projectiles' final speed?

c.  How would you find the  angle at which the projectile hits the floor?

 

Today:

Rest of the week (tentative plan):

  • Tuesday -- create a trajectory spreadsheet
  • Wednesday -- begin trajectory contest project
  • Thursday -- continue project work
  • Friday -- test retake opportunity; Mr. Pennington's Unit 2 practice test

 

Homework:

Class 8.5 Friday, 9/17/21

Warm Up:  

1.  What do "air speed" and "speed in still water" mean?

2.  What is a "heading?"

3.  Let's practice resolving non-orthogonal vectors into their x and y components.

Identify the component and resultant vectors for the following "river problems."  Then sketch them using head-to-tail vector addition.

3.  A boat travels eastward at a rate of 3m/s.  The boat's heading is northeastward, and the boat's speed in still water is 8m/s.  What is the velocity of the water in which the paddler is paddling?

4.  A quadcopter has a velocity of 20m/s westward.  The wind is blowing southward at a rate of 10m/s.  What are the quadcopter's airspeed and heading?

5.  The driver of a golf cart on an aircraft carrier uses a compass to head northward.  The cart's speedometer reads 10mph.  The aircraft carrier's heading is eastward, and its speed in still water is15mph.  The ocean current is northwestward at a rate of 5mph.  What is the actual velocity (relative to the Earth) of the golf cart?

 

 

Today:

Homework:

  • River Problems 5-6.  These are non-orthogonal.  Solutions
Class 8 Thursday, 9/16/21

Warm Up:  

An airplane flying horizontally with a ground speed of 120 m/s releases care packages from a height of 4,800 meters.  If the packages are not affected by air resistance, how far ahead of the target (in the x dimension) should the packages be released?

 

Today:

Homework:

Class 7.5 Wednesday, 9/15/21

Warm Up:  

1.  Suppose the two vectors on the right represent two forces acting on the clam.  In what direction will the clam accelerate?  How will that acceleration compare to the accelerations we would observe if each force were acting alone?

2.  The diagram on the right shows a top view of a train car that is moving at a rate of 2m/s.  You are in the car.  In which direction and how fast should you walk in order to have the intended velocity shown on the right.

 

Today:

Homework:

  •  None
Class 7 Tuesday, 9/14/21

Warm Up:  None

Today:

  • Test

Homework:

  • None
Curling Technique — Curling — Jonathan HavercroftClass 6.5 Monday, 9/13/21

Warm Up:  How can we find the acceleration of an object as it slides across this floor, using only a stopwatch and the floor as measuring devices?

Today:

  • Check/review homework.
  • Interests of students in my two classes:
  • Questions about the test? -- Did anyone notice any more mistakes?
  • Here's a mostly nonsensical problem for the people who want to think about time travel...

If you could travel in time, and if you found yourself in the infinite loop of acceleration changes shown below... would you ever find yourself in the same location as another past self?  Explain by creating analagous graphs of velocity and distance vs time.

Homework:

  •  Study -- Hopefully you have been marking items in the notes and homework that were tricky the first time.  Go back and quiz yourself over those items.  They should no longer be tricky.  If they are, get help.  Memorize the formulas if you want an extra point. Kinematics formulas Quizlet
Class 6 Friday, 9/10/21

Warm Up:  

1.  Create a kinematics problems (on your own, or as a class).  Start by listing the available formulas and/or variable.

2.  If we graphed the motion of a vertically-launched projectile, which of these graphs would have at least one sharp corner in it? 

a. velocity vs. time    b. speed vs. time    c.  position vs. time    d. acceleration vs. time 

e. none of these    f. all of these

Today:

More Kinematics Practice (optional!)

  1. New questions and problems, based on form feedback...
    1. Extra Unit 1 Test Practice -- Questions and problems
    2. Extra Unit 1 Test Practice -- Answer Key The answer to #5 on the first section was wrong.  It should be correct now (if it's highlighted in yellow).  Solution to Extended Kinematics Problem
  2. Optional -- Here is some more practice creating graphs for events
    1. Blank PDF Handout -- "Extra Graphing Practice"
    2. Solutions(**On my graph of position vs time for the soccer ball kick, my graph should really have started and ended at the same position.)
    3. Video of me working through these and creating solutions
  3. Optional -- More practice with simple (one formula required) kinematics problems.  Make your own copy and expand column D to see the answers.

Homework:

  •  "Classic River Problem" on page 4 of the Unit 2 Packet.
Class 5.5 Thursday, 9/9/21

Warm Up:

Sketch a graph of acceleration vs. time for a suction cup Nerf dart that is shot at a wall.  Start your graph just before the dart begins to move, and end it just after the dart stops.

Today:

  • Check/review homework.  Improving our troubleshooting efficiency.
  • Pinpoint weaknesses.
  • Test on Tuesday:  42 points total
    • 16 multiple choice / short answer -- 1 point each
    • 1 unit conversion -- 2 points
    • 4 Problems -- 4 points each
    • Extended Problem -- 5 parts, worth 2 points each
    • Bonus (optional) -- 1 point if correct
    • 1 point for opting out of the formula sheet.
  • Fill out this form if you want to request extra practice.

Homework:

Class 5 Wednesday, 9/8/21

Warm Up:

Mr. Chase pointed out that there are 9 types of motion.  This is based on the fact that Velocity can be +, -, or 0, and acceleration can also be +, -, or 0.  A pendulum swinging back and forth demonstrates 8 out of these 9 types of motion.

1.  Graph the pendulum's X velocity over one full period (over and back) of motion.

2.  Identify where in the video each of those 8 types of motion occurs.

3.  Which of these 9 types of motion is not demonstrated?

 

Today:

Homework:

Class 4.5 Tuesday, 9/7/21

Warm Up:  Simplify this "extended" kinematics problem by drawing a diagram and identifying intervals with unique accelerations and or unique initial/final conditions.  You don't have to solve the problem.

A ball is dropped (in free-fall) from a height of 16m. When it reaches a speed of 3m/s, the ball contacts a compression spring.  The ball continues downward, slowing down as it compresses the spring and then speeding up as it is thrown back upward by the spring.  For purposes of calculation, you can consider the ball to experience a constant +35m/s2 acceleration during its 0.15 seconds of contact with the spring. 

1.  What is the height of the ball when the spring is fully compressed?

2.  What is the maximum height of the ball after it leaves the spring?

Today:

Homework:

Class 4 Friday, 9/3/21

Warm Up:   

1. Suppose students enter our school at a rate of 54 pounds/sec (pounds of student).  After they enter, they lie down,  head-to-toe, forming a line whose length is the sum of their heights.  Since an average 16 year old student's weight:height ratio is about 2.07 lb/in (and assuming these are all average students with that ratio), how many days will it take them to form a line 3 miles long?

2.  Is this actually a "possible problem," in the sense that it could happen and that it is solvable given the information above?

Today:

  • Warm-up -- discuss how dimensional analysis works.
  • Check/review homework
  • Spool tractor challenge -- accuracy and speed

Homework:

Class 3.5 Thursday, 9/2/21

Warm Up:

Consider the case of this ball.  At t = 0s, the ball is free-falling directly upward at a height o 10m, with a speed of 20m/s.  Sketch graphs of the ball's position, velocity, and acceleration (vs. time) over the next 4 seconds. [For simplicity, use g =10m/s2 instead of g = 9.8m/s2]

Today:

  • Check/review homework
  • Spool tractor practice

Homework:

  •  Complete the problems section of Mr. Pennington's Old 1-D Kinematics Test (Packet page 20). **Note that problem 1 is a unit conversion problem, which we haven't been over in class (though you should be well-versed in unit conversions from Chemistry).  You will have a chance to practice unit conversions if you want more practice.  And in problem #2 you'll need to know that circumference = pi*d.  Here's the Answer Key. If you have questions, watch this Video for Help with the Problems
Class 3 Wednesday, 9/1/21

Warm Up:

1. For letter a, on the right describe what an object could be doing in order to have both positive velocity and positive acceleration.

2.  Do the same for the rest of the letters.

 

Today:

Homework:

  •  Complete the rest of the multiple choice on Mr. Pennington's Old 1-D Kinematics Test (Packet pages 18-20).  Answer Key. If you have questions, watch this Video for Help
Class 2.5 Tuesday, 8/31/21

Warm Up:  What is a spool tractor?  How does one work?

Today:

 

Homework:

  • Complete Multiple Choice 1-12 from Mr. Pennington's Old 1-D Kinematics Test (Packet pages 17-18).  Answer Key. If you have questions, watch this Video for Help
Class 2 Monday, 8/30/21

Warm Up:

1.  Assuming that the man in the picture is 2m tall, and the frame rate of the camera was the usual 30 frames per second, what was the approximate maximum speed of the object?

2.  Based on your answers, do you think the assumption of 30 frames per second was too low, too high, or about right?

Today:

Homework:

Class 1.5 Friday, 8/27/21

Warm Up:

Use the velocity vs time graph on the right to sketch the shape of a corresponding position vs time graph.  [Assume that motion away from the sensor is positive, and motion toward the sensor is negative.]

Today:

Optional Reading -- Online Textbook:

Homework:

Class 1: Thursday, 8/26/21

Warm Up:  Suppose you're involved in a 2 lap race.  If you want your overall average speed to be twice as fast as your speed for the first lap, how much faster do you have to go during the 2nd lap? [To calculate average speed you can use rate = distance / time]

Today:

Optional Online Textbook Reading:

Homework:

Class 0.5: Wednesday, 8/25/21

Physics 200: Mr. Stapleton

Warm Up:

Spin one of the "sprotating cylinders" by pressing one end until it squirts out from under your finger.  Try pressing the other end.

When the cylinder is spinning, why do you only see the symbol that you press?

Slow motion

Today:

Links:

Online Textbook Reading:

Homework: None