Class 41: Friday, 1/10/25

Warm Up: 

In this video, a driver supposedly enters a loop-the-loop at a speed of 36mph (16.1m/s).  The driver supposedly experiences 6g at the bottom and approximately 0g at the top.  They say the loop is 40feet high, so the radius is approximately 6.1m. 

1.  Calculate the values of g experienced by the driver at the bottom and the top. 

2.  Why don't your calculations match theirs?

 

Today:  Review for the midterm

Homework: prepare for the :midterm
Class 40.5 Thursday, 1/9/25

Warm Up: 

1.  How much does a 100 pound person weigh on the ISS (International Space Station)?  Explain.

a. 0 pounds    b. 89 pounds    c. 100 pounds   d. 111 pounds

2.  Would a candle "work" on the ISS? 

 

Today:

Homework: prepare for the midterm

 
Image result for salad spinner diagramClass 40: Wednesday, 1/8/25

Warm Up:  What do all of these things have in common?

 

Today:

  • Test retake
  • Midterm
    • Question -- if there is a 2D Forces problem on the midterm, how would you like it to be graded?  The final answer, multiple steps, or optional partial credit for multiple steps
    • Midterm review -- no one has emailed me a request for practice problems

Homework:

  • Prepare for the midterm
Class 39: Tuesday, 1/7/25

Warm Up: 

1.  What would happen if you made a hole through the center of the Earth, and you jumped in? Spreadsheet calculations 
2.  If you made it all of the way through, where would you come out?  (antipodes map)
 3.  What's the orbital period of a low orbit satellite?  Assume, for the purpose of calculations, that the satellite orbits just above Earth's surface (with no air resistance). 
Earth's radius = 6.38x106 m.  G = 6.67x10-11Nm2/kg2.  Earth Mass = 5.97x1024kg

 

Today:

  • Midterm review
  • Update on bonus points for memorizing the midterm formulas

Homework:

  • Optional retake tomorrow.
  • Prepare for the midterm
Class 38.5: Monday, 1/6/25

Warm Up: 

1.  Can you guess what the "sisyphus train" does?

2.  How did it get that nickname?

 

Today:

Homework:

  • Review the old tests.  Come to class with requests for specific types of practice.
Class 38.5: Friday, 1/3/25

Warm Up:  How do you remove the coin from the YOT?

Today:

Homework:

Class 38: Thursday, 1/2/25

Warm Up:  What's happening to this guy?  Why?  How does it work? 

Today:

Homework:

Class 37.5: Friday, 12/20/24

Warm Up: Some cultures celebrate a character called Santa Claus, who delivers presents around the world in a sleigh.  This event occurs over a time interval known as Christmas Eve.  Starting from rest, if Santa were to deliver a present to every child who believes in him, how fast would Santa need to accelerate between stops in order to deliver all of the presents on Christmas Eve? Santa Claus from an Engineer's Perspective

 

Today:

  • Cozy, crackling fireplace
  • Return Tests
  • Discuss AP
  • Learn to secure a load with a bowline and a Trucker's Hitch (slippery half hitch + slip knot), and explain how this arrangement allows you to tie a load with high tension.
    • Here's a video showing exactly what to do.
    • Bowline:        Slippery Half Hitch:        Slip knot:        How to secure a box with a Trucker's Hitch:
    • **If you can still demonstrate this when we take the energy test, you can earn 2% bonus points on the test -- and you'll have an very useful skill!

Homework:

  •  None
Image result for wedge mechanical advantageImage result for hockey stick fulcrumImage result for boat winchClass 37: Thursday, 12/19/24

Warm Up: 

The pictures on the right all show simple machines.  Simple machines allow the same work to be done with more convenient combinations of force and distance.  In physics, "work" is equivalent to energy, and Work = Fd

1.  For each picture, identify the machine (s).

2.  For each machine, tell how the machine alters the distance over which force must be applied by the human using the machine.

3.  How does the machine alter the force that the human must apply?

4.  Which "machine" is fundamentally different? Why? 

 

Today:

  • Test: Circular Motion and Gravity

Homework:

  •  None
Class 36.5: Wednesday, 12/18/24

Warm Up: How hard would it be to pour a drink during a barrel roll?

 

Today:

  • Hot pink is the color that I used for wrong answers when I graded the corrected rocket project stuff.
  • Return retakes
  • Do this first -- today is a short class!
    • Check/review homework
    • Tomorrow's Test:
      • 5 Problems:
        • Vertical circle (top, bottom, or both)
        • Space station simulated gravity problem (essentially a horizontal circle problem)
        • g problem
        • Law of gravitation problem
        • Orbit problem
      • No problems requiring the Period (T) formula.
      • On the retake, you can retake any individual problem.

Homework:

  •  Test tomorrow:  Circular Motion and Gravity
Class 36: Tuesday, 12/17/24

Warm Up: 

1.  Which formulas will be provided on the test?

2.  Which formulas can be easily derived?

3.  For each formula...

a) to what situation does it apply?

b) to what does each letter apply?

 

Today:

  • Test Review
  •  Optional retake -- 2-D Forces test

Homework:

Class 35.5: Monday, 12/16/24

Warm Up: The car is driven at a constant speed through the loop-the-loop. 

1. Sketch a force diagram for each letter in the diagram.  Identify each force.

2.  Write an expression for normal force at each letter.

 

Today:

  • Check/review homework

Homework:

Class 35: Friday, 12/13/24

Warm Up: 

None

 

Today:

  • Mr. Stapleton is out of town. 
  • Work on the first practice test.  Use the solutions and video to check yourself and get help.  See "homework, below."

Homework:

  •  Due on Monday -- Handout p. 5-7 "Practice Test #1" Unit 5 Answer Key Video Explanations  Some of the problems have been skipped, since we're leaving out Kepler's laws this year.
Class 34.5: Thursday, 12/12/24

Warm Up: 

1.  Why do we have tides?

2.  Why is there a high tide on the opposite side of the Earth from the Moon?

3. Which object is excerting a greater gravitational force on you right now, the Moon or the Sun?

4.  How is this related to black holes?

 

Today:

  • Return tests.  Optional retake next Tuesday.
  • P. 3-4 of the Unit 5 Handout  PDF Unit 5 Answer Key -- using Newton's Law of Gravitation and deriving three useful formulas.  Video From Class
  • Mr. Stapleton gone tomorrow.  Work on the first practice test.  Use the solutions and video to check yourself and get help.  See "homework, below."

Homework:

  •  Due on Monday -- Handout p. 5-7 "Practice Test #1" Unit 5 Answer Key Video Explanations  Some of the problems have been skipped, since we're leaving out Kepler's laws this year.
Class 34: Wednesday, 12/11/24

Warm Up: None

 

Today:

  • Test  -- Forces in 2-D
  • Retake next Tuesday.

Homework:

  •  None
Class 33.5: Tuesday, 12/10/24

Warm Up: We don't have to answer all of these.

1.  What's the formula for the net force acting on the jogger in the video?

2.  Approximately how fast is the jogger in this video moving?

3.  If the jogger turned around and jogged the other way, would he feel any different?

4.  What must move in order for the person to experience simulated gravity... the space station, the person, neither, or both?  What does "move" mean in outer space?

5.  There are essentially two ways to simulate 1g of gravity in "outer space."  What are they?  How are they similar?  How are they different?  How do they compare to real gravity?

 

Today:

  • Check/review homework
  • Work on p. 3-4 of the Unit 5 Handout  PDF Unit 5 Answer Key -- Law of Gravitation and combining the law of gravitation with the centripetal force (or acceleration) formula. 

Homework:

  •  Test tomorrow
Class 33: Monday, 12/9/24

Warm Up: 

The ball is moving at a constant speed in a circular path. 

1.  What is the direction of its acceleration?

2.  How do we know this?

Today:

Homework:

Class 32.5: Friday, 12/6/24

Warm Up: The drawing on the right shows a top view of a car stuck in mud.  A tight chain has been hooked to the car's bumper and also to a large tree.  At this point, how could someone (theoretically) move the car forward by applying very little force?

Today:

  • Check/review homework
  • Return rocket acceleration graphs.  Grades should actually be out of 9.  I plan to add a point, so the total points for the project is 106 (Graph = 9; Video Analysis = 16; "9 Moments" = 81).  The two problems in the video analysis are worth 3 points and 5 points, respectively.
  • When you fix your spreadsheets, do not change the colors I have added.  Those will tell me which cells I need to re-check.
  • Coming Up:
    • Test next Wednesday
    • Begin Unit 5 (Circular Motion ) on Monday
    • Rocket Project corrections are due next Friday.
  • Work time

Homework:

Class 32: Thursday, 12/5/24

Warm Up: Cheryl wants to use some string and a nail to hang a treasured portrait of great-great-grandfather Ernesto as a young man.  The portrait is rather heavy.  Rank the three configurations on the right according to their risk of exceeding the breaking strength of the string. (Hint: draw a force diagram with arrows to scale).

Today:

  • Check/review homework
  • How to do the two remaining types of problems -- p. 6 (#3), then p. 5(#2)  Video from class

Homework:

  • #2 on p.5 and #4 on p.6
Class 31.5: Wednesday, 12/4/24

Warm Up: 

A 4 kg mass is suspended by an ordinary string from the ceiling of a fully-enclosed train car (with no vertical movement).  The car is on a level surface at sea level, and the angle shown remains constant.

1. How many of these can we deduce from this information?

A) The mass' direction of movement     

B)  The mass' acceleration

C)  The mass' speed

D) The string tension

2.  If you wanted to simulate this (i.e. make a mass hang "motionless," at an angle, like this), what would you have to do?

Today:

  • Check/review homework
  • Solve the warm-up -- find acceleration and tension of a mass hanging from the ceiling:  Video from Class

Homework:

Class 31: Tuesday, 12/3/24

Warm Up: In both situations on the right, a block slides along a surface without losing contact with the surface.  In past problems, the weight of a block sliding on a surface was always equal to the normal force.  For each of these situations, explain why the block's weight and normal force are different.

Today:

Homework:

Class 30.5: Monday, 12/2/24

Warm Up: In this next short unit, you will be finding all of the forces and accelerations in situations like those shown on the right.  What general problem-solving strategy(ies) might be helpful?

Today:

  • Preview of what's coming up...
    • Forces in 2-D (short unit -- 1 week)
    • Circular Motion
    • Midterm Exam
  • Rocket work time

Homework:

  • Finish the Water Rocket Project
Class 30: Friday, 11/22/24

Warm Up:  If you want help on any particular part of the project, pick a part now, and I'll show you how to do it.

Today:    

  • Discuss the height at launch and the height at the beginning of coasting.
  • Project work time

Homework:   

  • Projects are due on Tuesday.
Class 29.5: Thursday, 11/21/24

Warm Up:  How would you measure the force of water rocket thrust, with the rocket pointing upward?

Today:    

  • If you don't have good data for the water thrust part of the launch, you can use someone else's -- but you should do your own calculations.
  • Complete the rest of the water rocket project (handout 2 -- PDF) -- turn it in via Google Classroom  (unless you turn in a hard copy of the graph). 
  • Clifford Heath's Water Rocket Simulator

Homework:   

  • Optional -- work on the project. 
Class 29: Wednesday, 11/20/24

Warm Up:  

An acceleration graph for a rocket launch with a parachute might look something like this.

1.  Locate these moments in time ("snapshots" from the project).

a. sitting on the launch pad

b. Thrust phase

c. Beginning of coasting phase

d. Apogee

e. Moment during descent when net force is highest

f.  Just before landing

g. Impact

 

2.  How would this graph look different if there were no parachute?

Today:    

Homework:   

  • Optional -- work on the project. 
Class 28.5: Tuesday, 11/19/24

Warm Up:  Open Clifford Heath's Water Rocket Simulator and one of the trajectory spreadsheets that we have been using.  Find out what cross-sectional area he uses in his simulation.  To do this:

1.  Set his simulation to: water volume = 0.6, dry mass = 150g, Cd = 0.3, and pressure = 100p.

2.  Run his simulation and find his rocket's initial coasting speed by adding the burnout velocity to the speed increase due to air pulse.

3.  Set your spreadsheet air density to 1.23kg/m3 (approximately average)

4.  Use his burnout height as your initial y position, and match your other spreadsheet initial parameters to his.

5.  Adjust your cross-sectional area until your time aloft matches his.

Today:    

  • Decide on your rocket's cross-sectional area.  Then disassemble your rocket. 
    • Duct tape in the trash
    • Rebar (with hot glue removed) in the peanut butter jar
    • Intact bottles in a bag
    • clean plastic pieces in one of the box lids
    • Put extra caps on bottles
  • Begin the Water Rocket Modeling Project.  Work on Water Rocket Modeling, Part 1: Video Analysis, Calculations, and Two Problems (PDF)
    • Eventually, you will be entering your answers into this spreadsheet (so that I can easily check them).

Homework:   

  • Optional -- work on the project. 
Class 28: Monday, 11/18/24

Warm Up:  None

Today:    

  • Test retake
  • Work time (if you haven't finished the spreadsheet homework)

Homework:   

  • Check your Spreadsheet Quiz answers.  If you  missed any, and you don't know why, watch this video.   If you still have questions, ask them on Tuesday.
Class 27.5: Friday, 11/15/24

Warm Up:  Prepare to launch

  1. Measure your rocket's dry mass and record it.
  2. Carefully add 600ml of water to your rocket.
  3. Prepare to record launch videos
    • Make sure that your camera is recording at 240fps.
    • Hold your camera in landscape orientation.
    • Adjust your field of view.  The bottom should be even with the launcher base, and the top should be 3m above the base. 
    • Keep the camera motionless until the rocket leaves the launch field of view, then follow the rocket.  You may need to zoom out to find it.  It doesn't need to be large -- just visible.
    • Follow the rocket until its moment of impact.

Today:    

  • Launch.
  • Back in the classroom,
    • Estimate your rocket's cross-sectional area.
    • Make a copy of your video that just shows the initial launch, completely in slow motion.  Email this to yourself and your partner(s).
    • Save the video

Homework:   

  • Test retake on Monday
  • Check your Spreadsheet Quiz answers.  If you  missed any, and you don't know why, watch this video.   If you still have questions, ask them on Tuesday.
Class 27: Thursday, 11/14/24

Warm Up:  What's the best amount of water to put in a water rocket? [Find out, according to Clifford Heath.]  How does the amount of water affect force and overall acceleration?

1.  What happens if you don't add any water?

2.  What happens if you completely fill the rocket with water?

 

Today:    

  • Finish rockets and launch
  • Measure your rocket's dry mass.

Homework:   Spreadsheet problems in Google Classroom
Class 26.5: Wednesday, 11/13/24

Warm Up:  How can you make nice, straight, recyclable fins out of a 2-liter bottle?

Today:    

  • Test retake on Monday!
  • Check/review homework
  • Start building rockets.  Here's a basic design...
    • Make sure that your pressure chamber fits on the launcher (have Mr. Stapleton check).
    • Make sure that nothing intereres with the launcher jaws.

Homework:   If you have a smartphone that takes slow motion video, get prepared to take videos next class.  Here's how to do it on an iphone (if you have an Android, maybe someone else has suggestions)...

  1. Shut down and restart your phone (otherwise your fps settings might be out of whack)
  2. Open settings
  3. Open camera
  4. In "record slo-mo" set to 720p at 240fps (NOT high efficiency)
  5. In "Format," choose "most compatible." [so you can open the videos in vernier video analysis]
Class 26: Tuesday, 11/12/24

Warm Up:  

The diagram on the right shows a 2-liter bottle water rocket.  Mass has been added to the tip of the rocket's nose cone, and fins have been added to the back (bottom).  The nose cone sits loosely on a platform that is hidden beneath the nose cone's flange.  The nose cone and pressure chamber are not fused together, but they are connected by a string, which also connects to the parachute. Video of one rocket another video

1.  What makes the rocket move upward?

2.  Why do fins need to be added to the back of the rocket?  How does this work?

3.  Why does mass needed to be added to the front of the rocket?  How does this work?

4.  Aside from stability, what other reason is there for adding mass to the rocket?

5.  What's the purpose for the flange at the bottom of the nose cone?

 

Today:    

  • Debug the spreadsheets
  • Use your spreadsheet to find the drag coefficient of a ping pong ball.  Use the data below, which correspond to the table tennis ball drop video:
    • Y displacement = -4.9m
    • Air density = 1.253 kg/m3
    • Mass = 0.00189kg
    • Drop time = 1.167s
    • Cd =
  • A1 Class Data:  Vertical, upward table tennis ball launch:
    • Ball Mass = 0.00189kg
    • Ball Diameter = 4cm
    • Air Density = 1.277126 kg/m3
    •  Y displacement = -2.33m
    • Time aloft = 4.08s
    • Initial Speed, based on 0.005s time increments = 205m/s
  • A2 Class Data:  Vertical, upward table tennis ball launch:
    • Air temperature (F) =
    • Air pressure (inHg) =
    • Relative Humidity =
    • Air Density (kg/m3) =
    •  Y displacement =
    • Time aloft =
  • Make a modified version of the spreadsheet that is better for completing the homework assignment
  • Tomorrow -- Build Rockets:
    • Goal: design and build a rocket with the lowest drag coefficient
      • Uses no more than 1m of duct tape
      • Has a piece of rebar at the tip
      • Is designed to be taken apart, so that parts can be reused next year.
    • We're not doing parachutes this year, but some of these videos are probably still useful.  Especially the one(s) about fins Construction playlist
    • Here's a simulatorClifford Heath's simulation.

 

Homework:   Using your spreadsheet and the data collected in class (details above), find:

  1. Using the same velocity from #1, find the launch angle that gives a maximum range.
  2. If the same ball were launched horizontally at the speed of sound (use 343m/s), how far, horizontally, would it have to travel before slowing down to 50m/s?
Class 25.5: Monday, 11/11/24

Warm Up:  

1.  What force launches this game show contestant?

2.  Is this for real?  Could we launch a student this high?  How could we find out?

 

Today:    

  • Return tests
  • Debug the spreadsheets

Homework:   None
Class 25: Friday, 11/8/24

Warm Up:  None

Today:     Test

Homework:   None
Class 24.5: Thursday, 11/7/24

Warm Up:   In the absence of air resistance, the flight of a projectile looks like the picture on the right.  What does it look like with air resistance?

Today:

  • Test review?
  • Investigations with the spreadsheet and ping pong balls (mostly)

Homework:   Unit 3 Answer Key

  • Prepare for tomorrow's test
Image result for car skidding to a stopClass 24: Wednesday, 11/6/24

Warm Up:   If you need to stop a car quickly, why should you avoid locking the tires or skidding?  

Today:

Homework:   

  • Turn-in a copy of your spreadsheet to Google Classroom
Class 23.5: Tuesday, 11/5/24

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:   Unit 3 Answer Key

  • None.  Prepare for the test.  Write down questions that you would like to ask.
Class 23: Monday, 11/4/24

Warm Up:   The harpoonist in the diagram is accelerating in both the X and Y dimensions.  Draw a diagram showing all of the individual and net forces acting on the harpoonist.  Then find the X acceleration of the Harpoonist.

Today:

  • Check/review homework
  • Practice test work time. Treat it like a real test.

Homework:   Unit 3 Answer Key

  • Practice Test -- p. 21-24
  • Test on Friday (11/8)
Class 22.5: Thursday, 10/31/24

Warm Up:   Ryan Crouser (approximately 145kg -- not the guy in the picture) set a world record by throwing a 7.26 kg shotput 23.51m. 

1.  Estimate the speed of the shotput when it left his hand.  This can be quick.

2. Draw a system schema for the point in time where he is pushing the shotput with the greatest force.

3. Draw a force diagram showing all of the forces acting on Ryan at that time.  Estimate the forces.

Today:

Homework:   Unit 3 Answer Key

  • p. 19-20, 1-6 only (not #7 on p.20)
Class 22: Wednesday, 10/30/24

Warm Up:  

1.  How fast does chalk fall? Is it faster than a cat?... (My spreadsheet answer)  Why?

2.  Sometimes people celebrate special occasions by firing guns into the air.  Is this safe?

3. Why don't clouds fall out of the sky?

Calculated terminal velocities of various spheres.

Today:

Homework:   Unit 3 Answer Key

  • p. 17-18 -- on page 18, change the astronaut weight in #1 to 2,000N from 600lbs
Class 21.5: Tuesday, 10/29/24

Warm Up:   One end of a rope is attached to the Gladys' belt.  Gladys is pulling directly downward on the other end. Assuming that the pulley and rope are massless and fictionless, how much downward force must Gladys apply in order to ascend?  Gladys weighs 500N.

Today:

  • Check/review homework
  • If there's time, sketch force diagrams (individual forces and net force) for each of the following:
    1. A person standing in an elevator that is starting to ascend
    2. A person playing tug-of-war, beginning to be pulled to the right.
    3. A trampolinist flying upward through the air after jumping
    4. Someone standing in a a cruise ship that is traveling rightward but is slowing down due to  an iceberg collision
    5. Someone throwing a shotput to the left
    6. A rower in a boat's galley, moving righward at a constant speed while rowing the boat rightward
  • Unit 3 Handout (PDF)
  • Work time

Homework:   Unit 3 Answer Key

  • p.14 #1-4
  • p. 16, #8
Image result for cat falling from buildingClass 21: Monday, 10/28/24

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. When does a falling cat experience zero net force?

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

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

5.  What characteristics of an object contribute to its drag (a force resisting movement through fluids)?

Today:

Homework:   Unit 3 Answer Key

  • P. 11, problems 4-6.   
  • p. 15, #5
Class 21.5: Friday, 10/25/24

Warm Up:   Find the acceleration of the system on the right and the tensions in the two strings.  Assume that the entire system is frictionless and that the pulleys and strings are massless.

Today:

Homework: 

Class 21: Thursday, 10/24/24

Warm Up:   The 2nd diagram on the right is a System Schema representing the situation in the top diagram, where the "objects of focus" are the blocks.  For simplicity, the creator of the diagram has assumed that the blocks are frictionless but the person is still pushing them somehow.

1.  What is a system, in Physics?

2.  What does a system schema show?  In a system schema, what is the difference between the "objects of focus" and the other objects?

3.  How can a system schema clarify the application of Newton's 2nd and 3rd Laws to solving problems in situations like this?

4.  Let's create one for this situation, with the objects of focus being the book and apple.

5.  ... and another one for this situation:  a chair is pushed across the floor by a student, with realistic friction.  Assume that the student and chair are both objects of interest.

6.  Use one of the previous system scheme (4 or 5) to create a "free body" diagram showing the forces acting on one of the objects of interest.

Today:

Homework: 

  • Complete the Newton Sled Activity Newton Sled Activity PDF  Problem organizer PDF
  • Memorize the kinematics formulas (and the range formula).  Quiz tomorrow.  The quiz will be "write the 6 basic kinematics formulas, plus the range formula."  The answers will be .  You can have unlimited retakes of this quiz, but you may have to come to FLEX for some of them.
Class 20.5: Wednesday, 10/23/24

Warm Up:   The rower in the photo has a mass of 50kg and a leftward acceleration of 1m/s2.  She is pulling against the oars with a total force of 100N. Sketch a diagram showing all of the forces acting on the rower.  Find all of the forces' magnitudes.

Today:

  • Check review homework.
  • Check and make sure that we have problem-solving step zero in your notes.
  • Finish #6 of the Newton Sled Activity 

Homework: 

 
  • #6 A and B of the Newton Sled Activity
  • Memorize the kinematics formulas (and the range formula).  Quiz on Friday.  The quiz will be "write the 6 basic kinematics formulas, plus the range formula."  The answers will be .  You can have unlimited retakes of this quiz, but you may have to come to FLEX for some of them.

 
Class 20: Tuesday, 10/22/24

Warm Up:  On level ground, Tim begins sliding with a velocity of 6m/s.  If Tim's slide lasts for 2 seconds...

1.  What is the coefficient of kinetic friction between Tim and the slide?

2.  What is the broader implication, if we compare the acceleration due to friction and the acceleration of gravity, on level surfaces?

 Today:

  • Finish reviewing homework -- and check again
  • Newton Sled Activity PDF -- Discuss #1-5 in class.  Complete #6 for homework.

Homework: 

  • Complete questions 1-5 and part A only of Problem #6 from the Newton Sled Activity PDF
  • Memorize the kinematics formulas (and the range formula).  Quiz on Friday.  The quiz will be "write the 6 basic kinematics formulas, plus the range formula."  The answers will be .  You can have unlimited retakes of this quiz, but you may have to come to FLEX for some of them.
Class 19.5: Monday, 10/21/24

Warm Up:   The McMurtry Speirling can accelerate from 0-60mph in 1.4 seconds.  Its mass is less than 1,000kg. 

1.  Assuming that the car's acceleration is constant, what is the coefficient of friction between the car tires and the road?

2.  Is this the kinetic friction or static friction?  How do you know?

3.  Actually, this can can accelerate that fast with a coefficient of static friction closer to 0.7.  How is that possible?

 Today:

  • Return retakes
  • Check/review homework

Homework: 

  • None -- If you didn't finish page 16 (#1-7), finish it tonight. Unit 3 Answer Key 
Class 19: Friday, 10/18/24

Warm Up:   None

 Today:

  • Optional Test Retake:  Take as many of the pages as you want -- even if you didn't take them all the first time.

Homework:  DUE ON MONDAY
Class 18.5: Thursday, 10/17/24

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. 
1) Try it
2) Explain what's happening, in terms of static friction and kinetic friction?

 Today:

Homework:  DUE ON MONDAY

Class 18: Wednesday, 10/16/24

Warm Up:   Newton's 3rd Law tells us that forces always come in pairs, and that each force in a pair is equal to and opposite the other.  If that's true, how do you win at the game of tug of war?

 Today:

Homework: 

Class 17.5: Tuesday, 10/15/24

Warm Up:   video from class

 A common occurrence in physics problems is someone standing on a bathroom scale inside an elevator.

1.  Sketch vectors representing all of the forces (pushes or pulls) that are acting on the person in the elevator.

2.  Write Newton's 2nd law (applied to the person) and plug in any values that you can.

3.  Write an equation for net force as the vector sum of all of the forces acting on the person.

4.  Set those two expressions of net force (net force as m*a and net force as the vector sum of forces) equal to one another and solve.  Figure out what's "going on."

 

Today:

Homework: 

Class 17: Monday, 10/14/24

Warm Up:   Monkey and Hunter problem:

A green hunter and a blue hunter point their Nerf guns directly at a orange monkey and then fire simultaneously.  Just as the two hunters fire their guns, the monkey slips and freefalls from the treetop to the ground. Assuming that this takes place in a vacuum, whose (if anyone's) projectile hits the monkey?

 

Today:

Homework: 

Class 16.5: Wednesday, 10/7/24

Warm Up:   TBD

 

Today:

  • PSAT day.  Most students will be gone.

Homework:

  • Projectile spreadsheet
  • Bonus option:  For 3% added to your 2D kinematics test grade, create a river problem spreadsheet that works like this...
Class 16: Tuesday, 10/8/24

Warm Up:   If you wanted to launch a projectile from the launch point on the right, so that you would hit the target -- without hitting the ceiling or either of the two obstacles -- what launch angle and speed would you use?

This is a good application for a spreadsheet like this one.

 

Today:

Homework:

  • Complete the  "Projectile Motion Problems Spreadsheet" in Google Classroom.
  • Prepare for the test retake (next Friday -- 10/18)
Class 15.5: Monday, 10/7/24

Warm Up:   We have some new Vernier Force Plates.  What experiment(s) could we try with one?

 

Today:

  • How to make a spreadsheet

Homework:

  • None
Class 15: Friday, 10/4/24

Warm Up:   None

 

Today:

  • 70 minutes for the test -- pep rally today

Homework:

  • None
Class 14.5: Thursday, 10/3/24

Warm Up:   Is it literally possible to "pull yourself up by your own bootstraps?"  You may assume superhuman strength and/or speed.  Explain. 

 

Today:

  • A1/2 -- return retakes
  • Check/review the homework.
  • Test review  -- update: Due to the short class, I removed all but 6 of the short answer/multiple choice section.
  • If we run out of test review ideas... create a projectile motion spreadsheet.  We will modify it later to include drag.

Homework:

  • Prepare for the test.
    • Know all formulas and variables (memorize if you can)
    • Know 1m/s = 2.24mph
    • Review problem-solving strategies for the types of problems that will be on the test (see class 13.5, below). 
    • Be aware of the "givens" that aren't really given in projectile problems.
    • Be able to add and resolve vectors in a variety of situations (projectile motion, river problems...)
    • Know all units
Class 14: Wednesday, 10/2/24

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?  What kind of pen would work better? 

 

Today:

  • Check/review the homework that I forgot to check yesterday.
  • Test review?
  • If we run out of test review ideas... create a projectile motion spreadsheet.  We will modify it later to include drag.

Homework:

Class 13.5: Tuesday, 10/1/24

Warm Up:   What will happen if I poke a knife through a potato, hold both objects in the air with the knife pointing downward, and then hammer the butt of the knife into the potato?  Why?  What if it's an apple, because I didn't have potatoes?

 

 

Today:

  • Check/review the homework that I forgot to check yesterday.
  • Review the spreadsheet solutions
  • Test format:
    • 10-15 6 short answer/multiple choice
    • 2 River problems with multiple parts (one orthogonal, one non-orthogonal)
    • 3 Projectile motion problems, each with multiple parts
      • Symmetric, Asymmetric, 1/2 Symmetric.
  • Next Unit -- Forces (Newton's Laws)
  • What sort of review help do you need?
  • Unit 3 Handout (PDF)

Homework:

  • Be ready for the test on Friday.  If you have questions about the test, we can discuss them.  Write down any questions that you have and share them tomorrow.
Class 13: Monday, 9/30/23

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:

  • Check/review the homework.
  • Finish the launcher challenge from last Thursday.  Hit a target on the wall, 1.2m from the floor, with a projectile launched at 10m/s and an angle of 35 degrees -- the projectile must be descending when it hits the wall.  While you're at it, find out everything else about this launch.  Complete this updated spreadsheet.  Get the updated one.
  • Tomorrow -- start something new and/or test review.  We can review more on Thursday

Homework:

  • Finish your spreadsheet and turn in to Google Classroom
  • Test Friday
Class 12.5: Friday, 9/27/24

Warm Up:  These are all of the variables that can be involved in projectile problems.  In the y dimension, all of our kinematics equations can be used. 

1.  What equations can be used to solve for things the x and the "x&y" dimensions? [Note: I've been saying there's only one formula for the x dimension, but that's not entirely true.]

2.  Projectile problems can be classified as symmetric, asymmetric, or "half of a symmetric" problems.  Give an example of each.

3.  Let's solve one.   Problem from A1 Class  Problem from A2 Class

 

Today:

  • Check/review the homework.
  • My plan is to have the test next Friday, but that's the pep rally day.  We could have it on Wednesday, instead.  What are your preferences?

Homework:

Class 12: Thursday, 9/26/24

Warm Up: 

1.  How does NASA simulate weightlessness?

2.  Is this really weightlessness?

Today:

  • Discuss recycling and composting
  • Check/review the homework.
  • Finish the projectile launcher challenge. 
  • New challenge.  Hit a target on the wall, 1.2m from the floor, with a projectile launched at 10m/s and an angle of 35 degrees.  You must fire two shots -- one  Complete this spreadsheet.

Homework:
Class 11.5: Wednesday, 9/25/24

Warm Up: 

An olympic athlete throws a javelin at an angle of 34 degrees, with respect to the ground.  The release point of the javelin is 1.3m above the ground.  The javelin travels a horizontal distance of 90 meters and lands after a flight lasting 3.7 seconds. 

1.  At what angle is the javelin sticking out of the ground at its point of impact? [We will just do this one, but you might want to try #2 on your own.  Solutions are below.]

2.  It turns out that the field is not level.  How much higher or lower is the field at the point of impact, compared to the field at the point of release?

solution

video of solution

Today:

  • Check/review homework
  • Finish the projectile challenge.  First confirm your setting for the proper speed (it may have changed or you may have a different setup).
Homework:
Class 11: Tuesday, 9/24/24

Warm Up:  If you want to launch a projectile horizontally, from a height of 0.3m, and you want its initial speed to be 4m/s, you should adjust your launcher strength until it travels a horizontal distance of ___?___m.

Today:

Homework: Unit 2 Answer Key

  • #4 on page 9
  • Mr. Pennington's multiple choice on pages 10 and 11.

 
Class 10.5: Monday, 9/23/24

Warm Up:  Video of this warm-up -- drawing Vx, Vy, and V during projectile motion

The diagram on the right shows the symmetric trajectory of a free-falling projectile.  Sketch the diagram. 

1.  What does free-falling mean?

2.  At each labeled point (A, B, and D) show/label the projectile's overall velocity vector (v), x velocity vector (vx), and y velocity vector (vy).

 

Today:

  • Return retakes -- but some students haven't done the retake, so give them back to me for a while.
  • Check/review homework
  • Work time

Homework:

Class 10: Friday, 9/20/24

Warm Up:  None (so there's time for the retake)

 

Today:

  • Optional test retake
  • Work time for those not taking the test -- start on the homework, below.

Homework:   See class #9.5, below.
Class 9.5: Thursday, 9/19/24

Warm Up:  Here are a couple of 2-D motion simulations...

What's the ideal angle for launching a projectile, if you want it to travel the greatest horizontal distance?  Why is that angle best?

Today:

Homework:

  • Nothing is due tomorrow.  All of this is due on Monday.
  • #1 and #2 on page 8.
  • #1 and #2 on pages 17 and 18.
  • Unit 2 Answer Key
Class 9: Wednesday, 9/18/24

Warm Up:  Let's explore the "classic river problem" using some helpful tables (vector addition and kinematics)!  Here's a review of the problem...

An 80m wide river flows due south at a rate of 2m/s.   Jane and Bob are on the west bank of the river, and they want to travel to a point on the opposite bank, directly eastward from their starting point.  In still water, Jane and Bob can paddle a canoe at a speed of 3m/s.  On land, each of them can travel at a rate of 4m/s...

  • Jane's plan is to adjust her heading so that she travels directly eastward across the the river, in a straight line to the destination.

  • Bob's plan is to head due east and accept the fact that the current will carry him downstream.  When he gets to the opposite bank he will travel on land back upstream to the destination.

Whose plan will get them there fastest?

Video of the solution to the warm-up.

Today:

  • Check/review homework
  • If you're planning to retake the test on Friday, don't forget that review videos are available -- and that you can see me during FLEX -- and that you can email with questions.
  • I have added 4 new videos to the "Unit 1 Test: Videos..." material in Google Classroom.  These are general help with topics that people struggled with on page 2 and 4 of the test.
  •  Unit 2 Packet (PDF) Unit 2 Answer Key
  • Today's Lesson -- Solve an non-orthogonal river problem -- #4 on p. 5.  Video of solution from class -- at the very end, someone gives me the wrong angle for the inverse tangent of 61/71.  It should be 40.7 degrees, not 49.3 (the complement of 40.7).

Homework:

Class 8.5: Tuesday, 9/17/24

Warm Up: 

Sketch a head-to-tail diagram for each of the following.  Two "component" vectors should add up to the "resultant."  The trickiest part is identifying the resultant.  [A couple of methods: the resultant is... the dependent variable  or  the velocity of the "protagonist" relative to the Earth.]

 

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: --- I got rid of number 1.  Just ignore solution #1.

 

Today:

  • Check/review homework
  • Sign up for FLEX or email me if you need help preparing for Friday's test retake.
  • A1/2 -- I figured out how my spreadsheet worked --  Spreadsheet Solution
  • How to solve "river problems."  Do an example orthogonal problem.  Video from Today's class. 

Homework:

  • Complete #2 amd 3 -- Change the river's current to 2.5m/s on p. 5. Unit 2 Answer Key
Class 8: Monday, 9/16/24

Warm Up: 

1.  Find the missing values of Vx, Vy, and theta.

2.  In the diagram on the right, should Vy be -7m/s, instead of 7m/s?

Today:

Homework:

  • Finish the rest of the vector addition problems on page 3 of the packet.  Unit 2 Answer Key
  • For a fun, optional challenge: try the Classic River Problem (p. 4).  Don't look at the answer!
Class 7.5: Friday, 9/13/24

Warm Up: 

1.  Suppose the two vectors (arrows) 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:

  • Return tests.  Check for grading errors.
    • Test distribution after yesterday's classes Average 83.5  Median 88
    • Pages with the lowest scores: 2 (particularly #11, 12,14,16) and 4 (particularly part e, but not b)
  • Brief intro to vectors and trigonometry -- do some practice problems with the various functions and inverse functions (make a video).  Here are some example problems...

Homework:

  • None to turn in.
  • Optional:
    • Trig Practice:  your trigonometry knowledge is rusty or nonexistent, self-teach about using SohCahToa and inverse functions.   You should be able to find plenty of resources with an online search.
    • Prepare for the optional retake (next Friday, in class).  Watch the relevant provided videos in Google Classroom ("Unit 1 Test: Videos to prepare for the retake").  Sign up for my Flex if you want more help.

Class 7: Thursday, 9/12/23

Warm Up:  None

Today:

  • Test

Homework: None
Class 6.5: Wednesday, 9/11/23

Warm Up:  Velocity and Acceleration Combinations Practice Quiz.  Use this link to take the quiz. (Last year's average was 8.71, and the median was 100%.)

Today:

  • Check/review p. 24-25. 
  • Test review -- What do we need to work on?  What are your questions?

Homework:

 
Class 6: Tuesday, 9/10/24

Warm Up:  Consider the X dimension motion of a pendulum that is continually swinging back and forth (left to right and back).  Sketch a graph of acceleration vs time (and another helpful graph).  See if you can identify the "9 types of motion."  ** On your acceleration graph, I am only concerned with your signs being correct (+,-,0)

Today:

  • Check/review homework. 
  • Go over the format of Thursday's test:
    • 2 short answer describing one of the 9 types of motion
    • 5 multiple choice exploring the relationships between speed, velocity, and acceleration in several situations, including free-fall
    • 4 multiple choice matching graphs of position, velocity, and/or acceleration
    • 1 short answer drawing a graph of acceleration for some event (and a grading emphasis on the acceleration having the correct sign [+,-, or 0] at each moment in time.)
    • 4 multiple choice exploring the relationships between velocity, speed, displacement, and distance
    • 1 unit dimensional analysis (unit conversion) problem
    • 4 kinematics problems (some relating to free-fall) requiring a variety of formulas
    • 1 extended kinematics problem with 5 parts (requiring a variety of formulas) and 2 intervals of differing acceleration.
  • Work time -- Work on p.24-25 of the practice test -- we should have time to go over this together

Homework:

  • Prepare for Thursday's test.  If you want some extra practice, some material is listed in tomorrow's homework section, above.
  • If we didn't finish the practice test in class, finish it.  Unit 1 Packet (PDF) (Answer Key )
  • Review the packet and the test format above, and write down any questions that you want to ask in class tomorrow.  Look back at the problems or questions that you circled on your homework assignments, and decide whether you now understand the important concept(s) that are involved in those questions.
Class 5.5: Monday, 9/9/24

Warm Up:  The acceleration of gravity on the Moon is approximately 1/6 of the acceleration of gravity on the Earth.  How much higher would an object fly if it were thrown straight upward on the Moon? (assuming no air resistance, and that initial speeds are the same)

Higher resolution drop of feather and bowling ball

Today:

  • Check/review homework. 
  • Review the dynamics cart activity.  Identify the 9 varieties of motion (with regard to v and a), and describe what the cart was doing.

Homework:

Class 5: Friday, 9/6/24

Warm Up: 

1. Can you guess the significance of the graphic on the right?

2.  The dimensions of the floor tiles in this room are 1foot x 1foot.  Assuming that 1 foot = 0.305m, what is the average speed of a student who crosses 18 floor tiles in a time of 3 seconds?  Express the speed in m/s and miles per hour.

3.  How does dimensional analysis work?  On what basic mathematical premise is it based?

Today:

  • Check/review homework.
  • Run, Hide, Fight drill 
  • Introduce the extended problem
  • Work on the lab!

Homework:

Class 4.5: Thursday, 9/5/24

Warm Up:  Consider the case of this ball.  At t = 0s, the ball is free-falling directly upward at a height of 10m and 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

Homework:

Class 4: Wednesday, 9/4/24

Warm Up:  When you're preparing for a test, it is important to understand the scope of what you are expected to be able to do.  For your first physics test, the scope of kinematics problems is defined by the variables and formulas on the right*. 

1. Use some of the variables to create a physics problem that you could use to test yourself in preparation for the real test. 

2. Can you anticipate how I might go about writing several problems for the test?

*There are a few "formulas" that I did not list, because you are expected to internalize them -- for instance.

Today:

Homework:

  •  Complete the rest of the multiple choice on Mr. Pennington's Old 1-D Kinematics Test (Packet pages 17-19).  Answer Key . If you have questions, watch this Video for Help
Class 3.5: Tuesday, 9/3/24

Warm Up: 

I have a dynamics cart like the one in the picture.  With the cart starting from rest, I am going to push it rightward across my desk so that it will hit an obstacle and stop.  Sketch graphs of its velocity and acceleration for the event (from rest at the beginning to the stop at the end). [By the way, there is an arrow on this cart pointing in the direction that the software assumes to be positive.]

Today:

  • Check/review homework

Homework:

  • Complete Multiple Choice 1-12 from Mr. Pennington's Old 1-D Kinematics Test (Packet pages 16-17).  Answer Key  If you have questions, watch this Video for Help
Class 3: Friday, 8/30/24

Warm Up:  Mr. Chase once said that there are 9 types of motion...

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:

Class 2.5: Thursday,8/29/24

Warm Up: 

Match each position vs. time graph with the correct velocity and acceleration graph.

Today:

  • Check/review homework --
  • Work time

Links:

Homework:

Class 2: Wednesday, 8/28/24

Warm Up: 

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

2.  Where in the graphs is there acceleration (any change in velocity)?

3.  When would the subject be speeding up?  Slowing down?

Today:

Links:

Homework:

Class 1.5: Tuesday, 8/27/24

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]  Solution -- don't peek!

Today:

Links:

Homework:

Class 1: Monday, 8/26/24

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:

  • Business to take care of:
    • Cell phones into the caddy.  Caddy slots are assigned based on alphabetical order.  I'll give you the order.
    • Attendance -- learn names/pronunciations
    • Around the room:  sign-out sheets, passes, recycling, trash, cabinets (off limits without permission)
    • Do we want to get two more desks?
    • Some of you (every 3rd)... sign on to a laptop -- Username: guest-ehs    Password: guestehs
  • Get the Unit 1 Packet:
  • Preview
    • Of the year
    • This unit
  • Discuss split block times (link to bell schedule)
  • Discuss homework grading.
  • Motion Matching Activity -- do the activity and answer the questions on page 5 of the packet.  Work in groups of 2-3 students (no more than 4).  Alternate group members attempting the challenges.  The point is to make sure that you can perform the motions and understand the graphs.  Questions are on packet page 5.
  • Don't forget your phones!

Links:

Online Textbook Reading:

Homework: Finish the questions on page 5 of the packet (assuming that you haven't already finished them).