Class 41: Tuesday 11/10/2020

Warm Up:  Rocket Launch -- No Warm-up -- See you all Term 3!

  • Blue: 

    • Return retakes

    • Rocket launch +1% on the test for any rocket.  +3% if the time aloft is 8.5s or better.

  • Rocket Launch Results: 

    • Congratulations Gill and Wyatt (Gold group rocket winners) and Ollie, Sam, and Hussein (Blue/remote group winners).  Stop by my advisory (C211) on Thursday for Boston Cremes.
Class 40: Monday 11/9/2020

Warm Up:  Test today -- No warm-up

  • Everyone: 

    • Test retakes -- Blue people in-person. Gold and remote, check in first in Google Classroom.  You can check in as early as 1:05.  I will make your tests available early, so that you have time to print things out and get set up.

  • Blue:  Prepare for rocket launch tomorrow.  +1% on the test for any rocket.  +3% if the time aloft is 8.5s or better.

  • Gold: 

    • You're done after today -- until 3rd term.

    • Congratulations Gill and Wyatt (Gold group rocket winners).  Stop by my advisory (C211) on Thursday for Boston Cremes.

      •

    •  
Class 39: Friday 11/6/2020

Warm Up:  Rocket Launch -- No warm-up

  • Blue:  Prepare for rocket launch next Tuesday

  • Gold: 

    • Last in-person physics day until 3rd term!

    • Return tests.  Launch rockets

  • Everyone: 

    • Test retakes on Monday.

 
Class 38: Thursday 11/5/2020

Warm Up:  Test today -- No warm-up, no Meet

  • Blue:  Prepare for rocket launch next Tuesday

  • Gold:  Test today.  Rocket launch tomorrow.

  • Everyone: 

    • Test retakes on Monday.  I plan to share the solutions and a video explaining all of the test problems.  That should be available tonight or tomorrow.

    • Here's the bonus problem for the test.  It's really hard.  You can turn in the answer up to the last day of the term (11/10).  Please do all of your own work but you can ask me for clarifications if you want.

Class 38: Wednesday 11/4/2020

Warm Up:  We have really only dealt with 4 different kinds of forces.  Can you name them?

  • Everyone: 

    • Test review -- today is a chance to ask questions about the test.
Class 37: Monday 11/2/2020

Warm Up:  Test today -- No warm-up, no Meet

  • Blue:  Test today.  Rocket launch next Tuesday

  • Gold:  Make your rocket.  See Classroom for details.  Test on Thursday.  Rocket launch Friday.

  • Everyone: 

    • Test retakes on Monday, November 9th

    • Here's the bonus problem for the test.  It's really hard.  You can turn in the answer up to the last day of the term (11/10).  Please do all of your own work but you can ask me for clarifications if you want.

 
Class 36: Thursday 10/29/2020

Warm Up: 

1. Starting from rest1, a car accelerates2 to its maximum velocity, maintains that velocity3 for a few seconds, and then brakes as quickly as possible4, finally returning to rest. 

Show how the net force and the individual forces acting on the car change over time.   Use labeled arrows to show all of the forces (and the net force) acting on the car during each of these numbered time periods.

 

2. A 50kg rower accelerates at a rate of -1m/s2 due to her application of a 100N force to the oars.  Calculate and show all of the forces acting on the rower. [For further fun, you might draw the forces acting on one oar, or the forces acting on the boat itself.]

 

  • Google Meet: 

    • Questions about the practice test (last year's test)?
    • Here's the test format    pdf version
    • I'm going to leave the Meet running today, in case anyone from home wants to ask questions throughout class.  But I will stop the recording right after the warm-up.
    • We will have a rocket contest for donuts (or a gluten-free equivalent?) and extra credit!  But you will have to build your rockets outside of class.  On the plus side, materials are cheap, and making a rocket is easy; it's just rocket science.  Groups of 1-3 students are acceptable.  More details to come.
    • All that's left this term is the test, the retake, and the rocket launch.

  • Blue:  Test on Monday.  Blue rocket launch on Tuesday, November 10th.

  • Gold:  Test on Thursday.  Gold rocket launch on Friday, November 6th.

  • Everyone:  Retakes on Monday, November 9th.
Image result for car skidding to a stopClass 35: Thursday 10/29/2020

Warm Up:  If you need to stop a car quickly, why should you avoid locking the tires and skidding?  What type of friction stops a car?

 
Class 34: Wednesday 10/28/2020

Warm Up:  A person pushes a box with a force of 21N, as shown.  This causes the two boxes to accelerate.  If there is no friction between the boxes and their sliding surface...

1.  What is the "contact force" between the two boxes?

2.  What are all of the individual forces and net forces that are acting on each box?

 
Class 33: Tuesday 10/27/2020

Warm Up:  No warm-up today, to give retakers a little more time.

 
Class 32: Monday 10/26/2020

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 this table...

 

 
Image result for cat falling from buildingClass 31: Friday 10/23/2020

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?

 
Class 30: Thursday 10/22/2020

Warm Up: 

1. Which can you throw with more force, a Wiffle Ball® (0.045kg), a baseball (0.145kg), or a bowling ball (6.3kg)?  Or is there no difference?  Explain your thinking.

2. What limits the amount of force that you can apply when you throw a light object, like a Wiffle Ball, or a feather?

Interesting Link:  article about the fastest pitch ever thrown

 
Class 29: Wednesday 10/21/2020

Warm Up: 

Draw (or imagine) a diagram showing all of the forces that are acting on a person who is walking to the left.  Label the forces.
Class 28: Tuesday 10/20/2020

Warm Up: 

1.  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?

2.  What are some words that you can use to interrupt Mr. Stapleton if you're at home on the Google Meet?

 

  • Google Meet: 

    • Review the homework --  Homework participation is very important in this class.  
      • I have been thinking that not being able to physically walk around the classroom and check everyone's homework is a serious loss.
      • The strategy is this... you attempt all of the homework questions on time. You make note of the difficulties you're having.  You make a reasonable effort to resolve those difficulties on your own.  Finally, when you have a chance to ask questions about the homework in class, you ask about whatever you couldn't figure out on your own.  Whether you are in-person or remote, you persist in asking your questions until things make sense.  Furthermore, when you finally figure things out, you make some notes so that you can remember the fix for the difficulty you were having. [**If you have been skipping class, not attempting the homework, or you've generally not been holding up your end of the bargain, this deal does not necessarily get extended to you.]
    • Notes: Tension and Systems pdf version

  • All Students -- Practice: 

    • Review other homework problems or prepare for your test retake.
Class 27: Monday 10/19/2020

Warm Up: 

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

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

 
Class 26: Friday 10/16/2020

Warm Up: 

1.  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?

2.  Newton's 2nd Law says Fnet = ma.  I have emphasized that ma equals the net force acting on an object.   In light of this, is it really okay to calcultate a 1kg brick's weight using the method on the right?

 

 

 
Class 25: Thursday 10/15/2020

Warm Up:  None

 
Wednesday 10/13/2020 -- No Google Meet today.  Mr. Stapleton is proctoring the PSAT.
Class 24: Tuesday 10/13/2020

Warm Up:  None

  • No Google Meet Today

  • All Students -- Practice:  This is due on Thursday, since there is no class tomorrow, due to the PSAT.
Class 23: Thursday 10/8/2020

Warm Up:

1.  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? 

 

  • All Students -- 1:30 Google Meet -- Use the link in Google Classroom (or watch the video -- class playlist).

  • All Students -- Practice:

  • Next few classes:  2 assignments and a test,

    • Tuesday -- Blue Test.  Gold will have an assignment.

    • Wednesday -- Short Meet for everyone.  There will be an assignment that will be due on Friday.

    • Thursday -- Gold Test

    • Friday -- Back to "normal."  Return and discuss tests.  Go over homeworks.  Time for something new???

  • Gold Students:

    • Mr. Stapleton Slidshow

    • Return tests

    • FYI, Mr. S. will be rushing home to get there in time for Zoom conferences.
Class 22: Wednesday 10/7/2020

Warm Up:

1.  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?

2.  1m/s = ____ mph.  For next week's test, memorize this or be able to calculate it based on a known conversion.

3.  Discuss #2 and 3 from yesterday's warm-up???

 

  • All Students -- 1:30 Google Meet -- Use the link in Google Classroom (or watch the video -- class playlist).

  • All Students -- Practice: None.  No homework
Class 21: Tuesday 10/6/2020

Warm Up:  1.  How would you solve this problem?

 

A forklift on an aircraft carrier is traveling with a velocity of 4m/s in a direction 32 degrees west of North, relative to the Earth.  If the aircraft carrier's velocity is 6m/s, in a direction 10 degrees east of North, what are the forklift's heading and speedometer reading? Video of solution

2.  Would this strategy work for a simple, orthogonal river problem?

3.  For any projectile problem, which kinematics formulas apply to the y dimension?  Which ones apply to the x dimension?

 
Class 20: Monday 10/5/2020

Warm Up:   How would you solve this problem?

 

A boat has a heading that is 25 degrees South of West, and its water speed is 14m/s.  The boat is traveling in a river with a current that is flowing at a rate of 5m/s in a direction 65 degrees East of South.  What is the boat's velocity, relative to the Earth?

Video of my solution

 
Class 19: Friday 10/2/2020

Warm Up:  

1.  Two of the vectors A, B, and C add up to the third vector.  Which is the resultant?

2.  Point D lies on the curvy path followed by an object.  How would we properly draw the object's V, Vx, and Vy at point D?

 

  • All Students -- 1:30 Google Meet -- Use the link in Google Classroom (or watch the video -- class playlist).
    • Discuss the homework. Remember that you're not expected to get everything right on your own.  If I was confident that you had already mastered these concepts, I would not have assigned this material for practice.  Between now and the next test we need to probe for your weaknesses and fill gaps in your understanding.  It takes a lot of practice to encounter all of the tricks that you will run into, and to learn how to deal with them.
    • When will you take the Unit 2 test?
  • All Students -- Practice:
  • In-Person Only: 
    • Retake opportunity -- please return your original tests so that I can see you section scores and update your overall grade.
    • Work time
Class 18: Thursday 10/1/2020

Warm Up:  

1.  List all of the basic formulas that will be provided (if you choose to accept them) on the next test.

2.  Drawing from that list of formulas, derive a specific formula for calculating the initial velocity (vo) of a projectile that is launched horizontally from a height (h) above the floor and which travels a horizontal distance x before landing on the floor.

 
Class 17: Wednesday 9/30/2020

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?

 

  • All Students -- 1:30 Google Meet -- Use the link in Google Classroom (or watch the video -- class playlist).
    • Discuss homework.
    • Questions about the retake?
    • Introduction to creating spreadsheets using formulas.  Discuss possible contest.  Big hint: if you have a spreadsheet question, you can ask me, but you can also Google it.
  • Gold Students:  Gold students, begin your retake tomorrow. (blue and remote on Monday and Tuesday)
  • All Students -- Practice:

    • Class #17 Assignment: Create a projectile trajectory model (spreadsheet) and use it to solve this problem (highlighted in yellow)...   Suppose you want to shoot a projectile so that it travels 3m horizontally before returning to its starting height, and so that its vertical displacement is 4m after traveling 2m horizontally (see diagram).  Solve this by guessing and checking (try angles and initial velocities until you get the right trajectory).  Stapleton answer -- I'll show you tomorrow.  Stapleton basic spreadsheet  Note: it is likely that several of you will do your best, but you will still run into some glitches in creating your spreadsheets.  That's okay.  Just give it a shot.  I can help you troubleshoot later.  Doing exactly what I do in the videos should work for you.

      •  Here is a Here is a link to a Spreadsheet Template that you can use.  Given an initial projectile speed and launch angle, your spreadsheet must:

        • Calculate the x and y position of your projectile at incrementally spaced moments during its flight.

        • Provide a graph of y displacement vs x displacement for the entire flight.

      • Use this screenshot to confirm that your spreadsheet works correctly.  Enter the same values in yellow, and see if you get the same results.  Your graph may vary depending on how many data points you include.  You may want to add a trend line. 

      • For videos showing how to create and fine tune the spreadsheet, see last year's videos on my YouTube channel.
Class 16: Tuesday 9/29/2020

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

 
Class 15: Monday 9/28/2020

Warm Up:  A green hunter in a treetop points a gun at a fake orange monkey and fires.  Just as the hunters fires the gun, the fake monkey slips and freefalls from the treetop.  Assuming that the monkey and the bullet to do not hit any obstacles besides one another, does the monkey get shot?  Explain.  [You may also assume that the bullet does not encounter any air resistance.] 

 
Class 14: Friday!!! 9/25/2020

Warm Up:  

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

2.  What is a "heading?"

 

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?

 

  • All Students -- 1:30 Google Meet -- Use the link in Google Classroom (or watch the video -- class playlist).
    • Return and go over tests (thoroughly).  I will video, but I will make the video unlisted and send you a link.  After a few days, I will make it private.
    • Briefly touch base on recent assignments and talk about your progress.
    • Retakes will be offered next Thursday and Friday (Gold), and the following Monday and Tuesday (Blue and Remote)
  • All Students -- Practice:
    • No new homework.
    • Catch up / Brush up on any of this week's assignments that need more attention.
    • Prepare for the retake -- In general, each question or problem will have a comparable counterpart (testing the same concept(s)) on the retake.  For example, the problems should be solvable with the same formulas, but you may be asked for different variables, and the scenarios will be new.  The order will also vary.  The extended problem may have parts that use require formulas than the original test.
  • In-Person Only: 
    • Mr. Stapleton slideshow
    • Anyone ready for a Trucker's Hitch test?
Class 13: Thursday, 9/24/2020

No Warm-up 

 
Class 12: Wednesday, 9/23/2020

No Warm-up 
Class 11: Tuesday, 9/22/2020

No Warm-up
Class 10: Monday, 9/21/2020

Warm Up:  

1.  The position vs. time graph on the right is intended to show two intervals of constant acceleration. Find the approximate values of those two accelerations.

2.  If we have time, sketch an acceleration vs. time graph of a pedestrian's left foot.

 

  • All Students -- 1:30 Google Meet -- Use the link in Google Classroom (or watch the video -- class playlist).
    • Discuss the homework and other items that were added to last class (green highlight)
    • Questions about the test?
    • No Google Meet Tomorrow or on Thursday.  Wednesday Meet is Gold and Remote only.
  • Blue Cohort:
    • Get rope.  When you have time (probably after the test), learn to secure a load with a Trucker's Hitch.  See details from last class -- especially Video #1.
    • Test tomorrow.  Study.
  • Gold Cohort:
    • Unit 2 Assignment  #1 -- Vector Addition: 
      • Here are the first few handouts for this unit [Combined handout with notes, vector addition practice, and river problems  Word version].  I'm sorry I didn't already copy these for you.
      • Watch the Video and take notes (or print them, or just find them on my website when you need them):
        • Introduction to the new unit (kinematics in 2 dimensions), Mr. Pennington's brief notes
        • Head-to-tail Vector addition (last year's warm-up) -- the relationship between the components and resultant.  Adding vs. resolving.
      • Complete the vector addition practice.  Here are my solutions. I included the answers after #6.  I did them quickly.  Let me know if I made any mistakes.
Class 9 Friday, 9/18/2020

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.  This video of a spring-bound object oscillating on an air track demonstrates 8 out of these 9 types of motion.

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

2.  Which type of motion is not demonstrated?

 
Class 8 Thursday, 9/17/2020

Warm Up:  

What would the graphs look like if you graphed acceleration for these event #2?  We are only doing #2 together, but try the rest if you want. My answers -- Note that my total areas under the curve for 1 and 2 should be zero, but they're not.  I should re-do them some day.

1.  A PE student runs from one end of the gym to the other and back (wall to wall) as fast as possible.

2.  A basketball is dropped from high above a gym floor and bounces back up until its velocity reaches zero.

3.  A skydiver steps out of a plane, begins to fall, opens a parachute, falls some more, and hits the ground.  [Assume all motion is vertical.]

4. How would you use dimensional analysis to convert 4m/s to mph?  Mathematically speaking, why does dimensional analysis work?

 
Class 7 Wednesday, 9/16/2020

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

 

 
Class 6 Tuesday, 9/15/2020

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.

  • All Students -- 1:30 Google Meet -- Use the link in Google Classroom (or watch the video -- class playlist).  *** I'm stopping this meet at 2:00 today -- unless people want to stay later for questions.
    1. Homework questions?
    2. Optional:  Memorize kinematics formulas for extra points on the test.  You can use this Quizlet.
    3. Unit conversions (by multiplying by 1) -- example -- convert feet per day to meters per second
  • All Students -- Practice:  
    1. Complete the rest of Mr. Pennington's Old 1-D Kinematics Test Answer Key. video help
    2. Optional homework in case you want unit conversions practice -- Unit Conversions Practice
  • In-Person Only::
    • Mr. Stapleton Slideshow
    • Preview of shelter project
    • Work time?
Class 5 Monday, 9/14/2020

Warm Up:  In the physics world, an object is in "free-fall" as long as gravity is the only force acting on that object.  The object may free-fall upward or downward.  Near the Earth's surface, the acceleration of free-falling objects due to gravity is approximately -9.8m/s2. 

Consider the case of this ball.  At t = 0s, the ball is free-falling directly upward 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]

 
Class 4 Friday!!!!, 9/11/2020

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.

 
Class 3 Thursday, 9/10/2020

Warm Up:

Use the velocity vs time graph on the right to sketch: a position vs. time graph.

 

  • All Students -- 1:30 Google Meet -- Use the link in Google Classroom (or watch the recording later on the class YouTube channel). Just in case I mess up today's video, here's a video of the same notes from 2017.
    • Did anyone watch the motion matching video and have questions about it?
    • Review/Discuss the homework
    • Mr. Stapleton Slideshow -- pictures since last September
    • Complete Acceleration Notes -- Answer Key
  • All Students -- Practice:  
    1. Complete Graph Comparisons [p.7 & 8 of the Unit 1 Handout]    Graph Comparisons solutions  Extra Video Help
    2. Mark this assignment complete in Google Classroom!
  • In-Person Only:
    • Get physical copies of the handouts for this week and next.
    • Practice names/pronunciations
    • Work time
    • Relax? Go outside?
  • Mr. Stapleton Only:
    • Don't forget to enter attendance!

 

 
Class 2 Wednesday, 9/9/2020

Warm Up:

For each letter, describe what is happening to the person's speed and direction during the 10 seconds represented on the graph.  

 

  • All Students -- 11:05 Google Meet -- Use the link in Google Classroom (or watch the recording later on the class YouTube channel).
    1. Warm-up
    2. Reminder that this hybrid model thing is an engineering work in progress. We can try different strategies.  Share your ideas.
    3. Briefly review the homework -- Take a quick look at the answers.  If you want more explanation, watch this video.  If you still have questions, ask them tomorrow.
    4. Notes:  Work through 1-D Kinematics notes. Here is a filled-in version: 1-D Kinematics notes Answer Key
      • Gold and remote cohorts won't have physical handouts.  I will have them available for the Gold group tomorrow.  If remote students want paper copies, we can work out some method of pickup.
  • All Students -- Practice: 
    1. Complete #5-8  [p.5 of the Unit 1 Handout] in 1-D Kinematics notes 1-D Kinematics notes Answer Key
    2. Mark this assignment complete in Google Classroom!

 
Class 1: Tuesday, 9/8/2020

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: