Summer Break!

Class
77
Monday, 6/1 The last day of physics! The test will be in Google Classroom, so check that out. Technically, the test is due tomorrow, because I'm not allowed to give a due date past tomorrow. But you can turn it in late if you want. The test and the bonus problem are attached separately to the assignment. If I don't see you at the Zoom meeting, have a great summer! Mr. Stapleton 
Class
76
Wednesday, 5/27 WarmUp : 1. Identify any nodes and/or antinodes in this video of the "wave pool." 2. Which harmonic is this? Could there be other harmonics? 3. Two important waverelated terms are resonance and forced vibrations. What do the two terms mean, and how are they related? Which one applies to the body of an instrument? Which one applies to breaking glass with your voice? How about the Tacoma Narrows Bridge collapse?
The Plan  Choose Your Own Adventure: Alas, our time has been cut short. Next Tuesday is now the last day on which an assignment can be made due. I had really hoped that we would have time to wrap things up with a test and a class project. Then I thought we could just do the project and that would be more fun and better for everyone. But now I realize that many of you would prefer the test. It would be less work, and it would probably be better for helping you to learn the core material. The best thing to do is to give you some choices. Here they are...
No matter which choice you choose, you can fix it, retake it, turn it in late, etc. up to June 12th. By the way, the test will have a bonus problem, which you can solve for extra points on any of the three options  but I anticipate it being difficult :). 
Class
75
Wednesday, 5/20 WarmUp : In this video of Chladni patterns, does the white substance (salt? powder?) settle at nodes or at antinodes? Why?
Today's Work:
Extra Stuff : 
Class
74
Monday, 5/18 WarmUp : If you're standing next to a race track, what do you hear as the cars pass you? a. Their pitch changes from high to low. b. Their pitch changes from low to high. c. There is no change in pitch.
Instrument Update  Instrument construction playlist
Today's Work:
Extra Stuff : 
Class
73
Wednesday, 5/13 WarmUp : The frequency of a wave describes number crests or troughs that pass a particular point in a given amount of time (a.k.a. cycles per second). The units are Hertz (Hz). 1. What is the approximate frequency of the waves on the right? 2. If the distance between two successive crests (i.e. wavelength) is 4m, what is the speed of the waves on the right? 3. What is the formula for wave speed, in terms of frequency and wavelength? 4. What's wrong with the cat's motion?
Today:
________________________________________________________________

Class
72
Monday, 5/11 WarmUp : No warmup. Test today.
Today:

Class
71
Wednesday. 5/6 WarmUp : If we have time, discuss Class 69 warmup.
Today:

Class
70
Monday. 5/4 WarmUp : Imagine a 110V home circuit that powers two light bulbs, a 100W bulb and a 60W bulb. 1. Is the circuit most likely a parallel circuit or a series circuit? How do you know? 2. Which bulb will burn brighter when they are both turned on? 3. Through which bulb will more current flow? 4. Which bulb has a higher resistance? 5. Why do the bulbs use more power than the wires that carry current to the bulbs?
Today: Kirchoff's Rules  another tool for determining currents in circuits.
Optional  you may want to try this pHet simulation  DC Circuit Construction Kit. You can use it to calculate currents and voltage drops in circuits (here's how). 
Class
69
Wednesday. 4/29 WarmUp : Assuming that the wires on the right have zero resistance... 1. What is the equivalent resistance of the entire circuit? 2. How much current flows through the resistor on the far right? 3. Can you identify at least one easy way and one hard way to answer questions 1 and 2? 4. The graph below shows current flowing through a light bulb at a variety of voltages. What does the slope of this graph represent? Do these light bulbs obey Ohm's Law? Today: Chapter 20.4 is the section that I skipped over in the last class. After today, the only new material to learn in this unit is Kirchoff's Rules. We may do a little more practice

Class
68
Monday 4/27 WarmUp : Check out the active graphic DC Circuit Water Analogy at Hyperphysics.com. According to the analogy...
1. Voltage is like _____ 2. Resistance is like _____ 3. Current is like _____
You should also check out this warning about how this analogy may cause some confusion for you in the future. Today: Normally, we do all of the notes below at one time. Given the circumstances, I am going to skip over parts of the notes in order to focus on resistance and calculating equivalent resistances in series and parallel circuits.

Class
67
Wednesday 4/15  Last B day before break!
Today:

Class
66
Monday 4/13 [Next class on Wednesday  Then it's
the weekend! spring break!
(except for flex/homework/selfcare Friday)] WarmUp : 1. What can Tango and Cash teach us about electricity? 2. If you had to choose between touching a suspicous wire with the back of your hand or your palm, which should you choose? Why? Today:

Class
65
TuesdayWednesday 4/7 4/8, 2020 WarmUp : None Today's Stuff

Class
64
FridayMonday 4/3  4/6, 2020 WarmUp : Suppose the neutral conductor in diagram A is placed in the electric field shown in diagram B. 1. How will the charges that are currently shown on the conductor rearrange themselves? Assume that both positive and negative charges can move equally well. 2. How will the electric field lines rearrange themselves? 3. Diagram C shows two conductors with excess positive charges. Why do the excess charges reside on the conductors' surfaces? Why are the charges closer together near the pointy part of the rightmost conductor? What implications does this have for Van de Graaff generator design? Today's Stuff (See specific completetion requirements/assignments in Google Classroom):

Class
63
WednesdayThursday 4/1  4/2, 2020 WarmUp : How does a Van de Graaff Generator Work? MIT video  inducing dipoles with a VDG If I have time, I'll provide my own, simplified, explanation of how VDGs work.
Today's Stuff (See specific completetion requirements/assignments in Google Classroom):
______________________ In case you want to get ahead, here's what's coming next (I think)

Class
62
MondayTuesday 3/303/31, 2020
The website is back! I'm going to be doing a hybrid Google Classroom/Website system. WarmUp : The electrophorus is charged by rubbing a cat(fur) against the top of an insulating plate (I). Then the conducting plate (C) is placed on top of the insulating plate and is touched by the physicist. Assuming that the cat fur has a strong affinity for negative charge... 1. What is the charge of the plate after it is touched by the scientist? 2. Explain how the conducting plate becomes charged. 3. What is the ground in this demonstration?
Givens for 2nd Retake (Test Version 3) Today's Stuff (See specific completetion requirements/assignments in Google Classroom):

Class
61.5
Friday, 3/27/20
I've moved into Google Classroom. Sort of sad. :(

Class
60
Thursday, 3/26/20
I've put today's stuff in Google Classroom. Please accept your invitation.

Class
59.5
Wednesday, 3/25/20
General Information

Class
59
Tuesday, 3/24/20
General Information
Work to do:

Class
58
Thursday, 3/19/20
Today:
_____________________________________ 12:06  Here's the fixed screencast explaining the test. More to follow...
11:45  Please watch this screencast that I just uploaded explaining the test. Be aware that the givens that I will be providing in PDFs will be different than those you see in the video. This test is our first hurdle. Don't worry; there will be retakes. ***I just realized that some of your last names were visible in the video. I will replace the video with one that doesn't show your names. The link above is to my Google Drive, so hopefully that will limit other people's access until I get this replaced. I will be adding more information here in the next half hour or so. Mr. S.
11:28 Update... I'm going to make a screencast explaining the test format and upload it. I may have to upload a couple, because the dirty dogs at Google decreased the time limit to 5 minutes. At any rate, I will explain what we're going to do for the test. I'll share the screencast with you, leave a link here, and then add links (here) to everything else you need in order to get going on the test. Mr. S.
Hi Physics 200 People! I was just in a hiring committee meeting, so I'm running a little behind. I wanted to have everything up here by the normal start of class, but I will probably be a few minutes late. It's 11:09 as I type this. If there's nothing more than this, check back in a half hour or so. Sorry for the delay! Mr. S. 
Class
57
Tuesday, 3/17/20
Warm Up: No warmup today. Today:
The highlight of today's class was this interesting (and fast) car! Click the photo to watch the video.
Check your email. I hope to start remote learning soon. Mr. S.

Class
56.5
Monday, 3/16/20
Warm Up: No warmup today. Today: Car project:
Rotational motion test:
Homework:

Class
56
Friday, 3/13/20
Warm Up: No warmup today. Today: Coming Up:
Homework:

Class
55.5
Thursday, 3/12/20
Warm Up: 1. Correction to 6d and 6f  please record deceleration times. 2. What's the contingency plan for this class if school is closed? 3. Good coronavirus article for teenagers. Important Covid19 graph . FYI, disease name vs virus name
Today:
Coming Up:
Homework:

Class
55
Wednesday, 3/11/20
Warm Up: 1. Derive a formula that will allow you to find the velocity of your car if you know its kinetic energy (and the wheel radii and moments of inertia). 2. How do you predict the maximum kinetic energy of a rubber band car (in order to predict maximum speed)?
Today:
Coming Up:
Homework:

Class
54.5
Tuesday, 3/10/20
Warm Up: 1. From a physics standpoint, how does a car pop a wheelie? 2. How can a car be designed to minimize or maximize wheelies?
Today:
Coming Up:
Homework:

Class
54
Tuesday, 3/10/20
Warm Up: 1. From a physics standpoint, how does a car pop a wheelie? 2. How can a car be designed to minimize or maximize wheelies?
Today:
Coming Up:
Homework:

Class
54
Monday, 3/9/20
Warm Up: A quadcopter has four propellers that usually alternate in their directions of rotation.
Today:
Coming Up:
Homework:

Class
53.5
Friday, 3/6/20
Warm Up: 1. What kind of rear tires do dragsters use? 2. Why do drivers do a "burnout" before each race? 3. In what other ways do dragsters increase traction?
Popular Mechanics Dragster Info
Today:
Homework:

Class
53
Thursday, 3/5/20
Warm Up: 1. What is the function of the steel spheres in this bearing? 2. A bearing reduces friction, but it is not frictionless. What are the sources of friction in this bearing? Fun Problems: 3. If the inner ring has an outer diameter of X, and the spheres have diameters of X/2, exactly how many revolutions do the spheres make for every rotation of the inner ring (assuming that the outer ring remains motionless)? 4. How many revolutions do the spheres make if the outer ring makes one rotation and the inner ring stays still? 5. What if each ring (outer and inner) makes 1 rotation, but in an opposite direction?
Today:
Homework:

Class
52.5
Wednesday, 3/4/20
Warm Up: Suppose you need three squares of toilet paper, and one of your hands is unavailable. 1. What strategy might you use to tear off only three squares? 2. Why is this task easier with a nearlyfull roll? 3. The custodians at Burlington High used to remove the rolls when they were almost empty, because it became nearly impossible to pull off more than one square at a time. Can you guess why?
Today:
Homework:

Class
52
Friday, 2/21/20
Warm Up: Rubber bands are not 100% efficient. If you do 2J of work in the process of stretching a rubber band, you won't get 2J of energy out of the rubber band when it snaps back. Suggest a simple way to estimate the efficiency of a rubber band.
Today:
Homework:

Class
51.5
Thursday, 2/20/20
Warm Up: No Warmup
Today:
Homework:

Class
51
Wednesday, 2/19/20
Warm Up: Falling cats continued... 1. Can we simulate what this cat does on a lazy Susan? 2. We have already agreed that you can't pick yourself up by your bootstraps. This video implies that you can turn yourself around boot straps (or maybe by a belt loop). Is this true?
Today:
Homework:

Class
50.5
Tuesday, 2/18/20
Warm Up:
Today:
Homework:

Class
50
Monday, 2/17/20
Warm Up: Suppose you need to want to build a camp fire. You have plenty of dry wood, but it's all big limbs that are too long to be manageable and too thick to break over your knee. Without using a saw or an axe, what's the best way to divide the wood into smaller pieces? Can you describe the proper technique? One solution.
Today:
Homework: Complete #12 in 1920 Rubber Band Car Problem Set 1 Solutions 
Class
49.5
Friday, 2/14/20
Warm Up: Explain how this jar lid closure works, in terms of Torque. You might also consider F=kx.
Today:
Homework: Complete practice problems #24 in 10.5 Angular Momentum Notes and Practice  Notes Key  Practice Key  Solution to #1

Class
49
Wednesday, 2/13/20
Warm Up: A sphere, a cylinder, a thin hoop, and a frictionless box are released from rest at the top of ramp. Their masses and heights are identical. 1. Rank the objects according to their arrival times at the bottom of the ramp. 2. Suppose the bottom end of the ramp is frictionless, and when they reach the bottom, the objects hit a vertical, frictionless wall. What motions, if any, would continue after impact? 3. How would the results be different if some objects had more mass or greater size than others? 4. How would the results be different if the ramp itself were frictionless?
Today:
Homework: Finish all of the practice problems in Notes and Practice: Dynamics of Rotation and Rotational Kinetic Energy

Class
48.5
Wednesday, 2/12/20
Warm Up: 1. What does a differential do? 2. How does a differential work?
Today:
Homework:

Class
48
Tuesday, 2/11/20
Warm Up: None
Today:
Homework:

Class
47.5
Monday, 2/10/20
Warm Up: 1. Where does a compound bow store most of its energy? 2. What purpose(s) do the pulleys of a compound bow serve?
Today:
Homework:

Class
46.5
Thursday, 2/6/20
Warm Up: In the rotational (angular) motion unit, we will be using new units that are analogous to our current, linear units. You will need to be able to work in radians. 1. 360º = _____ radians 2. 90º = _____ radians Today:
Homework:

Class
46
Wednesday, 2/5/20
Warm Up: 1. Suppose you need to screw an abutment into a fixture that is implanted in someone's jaw. How can you make sure that you screw it in just tight enough, but not too tight? 2. What predictable effects (if any) does an increasing e have on collision time and collision force? Today:
Homework:

Class
45.5
Tuesday, 2/4/20
Warm Up: Suppose some hard objects collide with one another. Then the collision is repeated, controlling all variables except that the collision is now cushioned.
1. In which case do the colliding objects experience a higher impulse? a. When the collision is cushioned b. When the collision is not cushioned c. Can't tell
2. In which case do the colliding objects experience a higher maximum force? a. When the collision is cushioned b. When the collision is not cushioned c. Can't tell
Today:
Homework:

Class
45
Monday, 2/3/20
Warm Up: A lowfriction physics cart is release from rest. It travels down a ramp, hits a spring, and bounces back up the hill before returning back down the hill again and continuing to bounce. If the cart travels 0.8m on its way down the ramp (0.8m = "closing distance") and 0.6m on its way back up the ramp (0.6m = "separation distance"), what is the coefficient of restitution (e) for this collision?
Today:
Homework:

Class
44.5
Friday, 1/31/20
Warm Up: Renault Modus (compact car) vs. Volvo wagon in a headon crash. (start at 4:30) 1. What happens? 2. Which is safer, a car that crumples in a crash or a car that is more rigid? 3. What questions remain after watching the video?
Today:
Homework: 
Class
44
Thursday, 1/30/20
Warm Up: Suppose I stand a board on end and shoot it with a Nerf^{ ® }dart. 1. Am I more likely to knock the board over if I use a dart that sticks to the board or if I use a dart that bounces off of the board? Why? 2. Which experiences a greater impulse, the dart or the board? Or do they experience the same impulse?
Today:
Homework:

Class
43.5
Wednesday, 1/29/20
Warm Up: 1. Into which end of the "potato launcher" barrel should the projectile be placed before firing? Why? 2. What length barrel will give the projectile the greatest speed? [We have barrels up to 10 feet long. ] 3. Which new concept best explains the answer to #2  Conservation of Momentum or Impulse? 4. If we measure actual velocities of the projectiles, using photogates, and compare those to our predicted velocities, how do you think they will compare?
Today:
Homework:

Class
43
Tuesday, 1/28/20
Warm Up: A steel ball, released from rest, rolls down a ramp in the classroom. Without using an electronic device, how might you determine the ball's speed at the end of the ramp?
Today:
Homework:

Class
42.5
Monday, 1/27/20
Warm Up: How can an understanding of momentum help you turn a towel into a better whip?
Today:
Homework:

Class
42
Friday, 1/24/20
Warm Up: 1. What will happen if I hold a tennis ball on top of a basketball and drop them to the floor together? 2. What if I reverse their positions? 3. Why does this happen?
Today:
Homework:

Midterm Stuff: Review Packet Anwers to Review Packet  3rd try Last year's Midterm Study Guide 
Class 41
Wednesday, 1/15/20
Warm Up: Midterm discussion  Questions? Remember that you can't leave early.
Today:
Homework:

Class 40.5
Tuesday, 1/14/20
Warm Up: No warmup today. Get started with the egg bungee activity.
Today:
Homework:

Class 40
Monday, 1/13/20
Warm Up: No warmup today. Get started with the egg bungee activity.
Today:
Homework:

Class
39.5
Friday, 1/10/20
Warm Up: You will be dropping an egg that will be stopped by a bungee. The force curves on the right represent force data collected from a variety of bungees. 1. Which bungee appears to behave like a spring with a constant k? 2. What does the area under each curve represent? 3. If these data sets were used to calculate work done by stretching the bungee, which set(s) would cause an overestimate of work? 4. If we used the bungee that has a welldefined k, and we estimate how far a falling egg will stretch the bungee, are we more likely to underestimate or overestimate the actual distance? Why?
Today:
Homework:

Class 39
Thursday, 1/9/20
Warm Up: None
Today:
Homework:

Class 38.5
Wednesday, 1/8/20
Warm Up: 1. When does each of these energy conservation equations apply to the diagram below? 2. Would your answer change if this were a completely frictionless environment?
Today:
Homework:

Class 38
Tuesday, 1/7/20
Warm Up: A spring hangs from the ceiling. When a mass m is attached to the end of the spring, released from that position, and allowed to come to rest, the end of the spring is a distance x lower than before the weight was added.
1. Which method below will not work for finding the spring constant k? Why? Method 1: Set the weight of the hanging mass equal to the spring force; mg = kx. This gives us k = mg/x. Method 2: Assume that the gravitational PE that is lost gets converted to spring PE, so mgh = 1/2 kx^{2} . Since the height lost is equal to the stretch distance (x), we find that k = 2mg/x.
2. Sketch a graph of PE, KE, and OE versus time.
Today:
Homework:

Class 37.5
Monday, 1/6/20
Warm Up: 1. A lightweight object and a very heavy object are sliding with equal speeds along a level frictionless surface. They both slide up the same frictionless hill.
Which rises to a greater height?
A) The lightweight object, because it weighs less.
B) They both slide to the same height.
C) The heavy object, because it has greater kinetic energy.
D) Cannot be determined from the information given.
Today:
?? Finish Notes: Springs + Odds and Ends Notes key Problem solutions
Homework:

Class 37
Friday, 1/3/20
Warm Up: energy skate parkSketch graphs of mechanical PE, KE, and OE (Other energy) versus time for... 1. Starting from rest, a child slides down a sledding hill of constant slope, reaching terminal velocity on the way. The bottom of the hill opens to a level meadow where the child comes to rest. 1b. Yesterday I gave you notes with this formula... KE_{i} + PE_{i} + W_{nc} = KE_{f} + PE_{f} + OE_{f} What is the problem with this formula, as it relates to the sliding child? 2. A dropped tennis ball bounces a few times before coming to rest. 3. A wad of soft clay flies horizontally toward a vertical wall. It hits the wall, falls a few meters to the floor, and comes to rest.
Today:
Finish Notes: Springs + Odds and Ends Notes key Problem solutions
Homework: Complete through Problem #4 in Pennington 20152016 test. #7 answer is incorrect Solutions 
Class 36.5
Thursday, 1/2/20
Warm Up: Sketch graphs of mechanical PE, KE, and OE (Other energy) versus time for a yoyo that goes down and back up (without human assistance) until it runs out of energy. [What do the steel balls and springs do? What is the yoyo's acceleration at the bottom?]Today: Notes: Springs + Odds and Ends Notes key Problem solutions
Homework: Problems 13 in Notes: Springs + Odds and Ends Notes key Problem solutions 
Class
36 Friday, 12/20/19
Warm Up: he 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. 1. Which "machine" is fundamentally different? Why? 2. Identify the task in each picture. 3. For each picture, identify the machine (s). 4. For each machine, tell how the machine alters the distance over which force must be applied by the human using the machine. 5. How does the machine alter the force that the human must apply?
Today:
Homework: If you didn't demonstrate mastery and understanding of the Trucker's Hitch, take a rope home and practice over break. 
Class
35.5 Thursday, 12/19/19
Warm Up: 1. Which planets have the fastest orbital speeds? 2. What would we have to do in order to change the orbit of a planet? (either move it away from the sun or toward the sun)
Today:
Homework: None 
Class
35 Wednesday, 12/17/19
Warm Up: None
Today:
Reading (optional): Homework:

Class
34.5 Tuesday, 12/17/19
Warm Up: 1. Can you guess what the "sisyphus train" does? 2. How did it get that nickname? 3. In the context of physics energy problems, some forces are called conservative, and others are referred to as nonconservative. Can you guess the difference between the two?
Today:
Reading (optional): Homework:

Class
34 Monday, 12/16/19
Warm Up: Do you know how to make a cloud in a 2liter bottle, using water and a small amount of smoke? Can you explain it in terms of work and energy?
Today:
Reading (optional): Homework:

Class
33.5 Friday, 12/13/19
Warm Up: 1. How are gforces dangerous to pilots? 2. In this video, a driver attempts to traverse a large looptheloop. In order to safely complete his mission, how many g's do you suppose the driver needs to tolerate?
Today:
Reading (optional): Homework:

Class
33 Thursday, 12/12/19
Warm Up: None.
Today:
Reading (optional): Homework:

Class
32.5 Wednesday, 12/11/19
Warm Up: The graphic on the right illustrates the possible scenarios for circle problems. Sketch or visualize a scenario based on each bullet point.
Today:
Reading (optional): Homework:

Class
32 Tuesday, 12/10/19
Warm Up: 1. What is a geosynchronous satellite? 2. What's the difference between a geosynchronous orbit and a geostationary orbit? 3. What is a space elevator? 4. In order to manually raise an elevator, would you have to apply a force greater than the elevator's weight? Explain.
Today:
Reading (optional): Homework:

Class
31.5 Monday, 12/9/19
Warm Up: None
Today:
Reading (optional): Homework:

Class
31 Friday, 12/6/19
Warm Up: From 20162017 EPS 200... The Sun, Earth, and Moon are continually spaghettifying one another. On Earth, we see the effects of this spaghettification in the form of tides. 1. What causes spaghettification? 2. How much gravitational force do the Sun and Moon each exert on 1,000,000 pounds of water? 3. Even if there were no water on Earth, there would still be tides, just as there are tides on the Moon. Describe these tides. 4. Why do we always see the same side of the moon? 5. Is the Earth's 24 hour rotational period speeding up or slowing down over time? Answer 6. Describe two ways to feel gravity.
Today:
Reading (optional): Homework:

Class
30.5 Thursday, 12/5/19
Warm Up: According to the diagram on the right... 1. At what approximate date is the Earth orbiting with the fastest speed? When is it orbiting the slowest? 2. Rank our seasons in order of length. Answer
Today:
Reading (optional): Homework: .

Class
30 Wednesday, 12/4/19
Warm Up: 1. Is this an answerable question  Approximately how fast is the jogger in this video moving? 2. If the jogger turned around and jogged the other way, would he feel any different? 3. 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?
Today:
Reading (optional): Homework: .

Class
29.5 Tuesday, 12/3/19
Warm Up: Consider a ball tied to the end of a massless string in the vacuum of space. The string is anchored at one end, and the ball is orbiting around the anchor point at a constant speed, held in its orbit by the string. 1. What forces are acting on the ball? 2. What forces are acting on the string? 3. How does this situation differ from the case of a realworld hammer throw (pictured on the right)?
Today:
Reading (optional): Homework: .

Class
29 Monday, 12/2/19
Warm Up: Why does tension show up so often in physics problems? Is tension overrated?
Today:
Homework: .

Class
28.5 Friday, 11/22/19
Warm Up: We skipped it.
Today:
Homework: .

Class
28 Thursday, 11/21/19
Warm Up: None
Today:
Homework: .

Class
27.5 Wednesday, 11/20/19
Warm Up: Are astronauts and candles weightless when they are in the international space station? What word best sums up their motion?
Today:
Homework: .

Class
26.5 Monday, 11/18/19
Warm Up: A waiter is delivering a chunk of bone, basted in synovial fluid, to some dinner guests. Touching only the serving tray (also made of bone), the waiter must deliver the dinner bone to the guests, and place it carefully on their table. Assuming the guests' table is to our left in the picture, describe what the waiter would need to do in order to make this happen? Can you sketch the forces on the bone?
Today:
Homework:

Class
26 Friday, 11/15/19
Warm Up: 1. Cheryl wants to use some string and a nail to hang a treasured portrait of greatgreatgrandfather 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. 2. How are static equilibrium and dynamic equilibrium different in physics problems?
Today:
Homework:

Class
25.5 Thursday, 11/14/19
Warm Up: A 1kg mass is suspended by a string from the ceiling of a fullyenclosed train car. The angle shown remains constant. 1. Describe the motions of the mass and the train car in qualitative terms. 2. How can we find the tension in the string? 3. How can we describe the motions of the mass and the train car in quantitative terms. Today:
Homework:

Class
25 Wednesday, 11/13/19
Warm Up: 1. 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. 2. This graph was created using a pressure sensor launched in a rocket during A5/6. Why does the sensor think the rocket falls to a negative elevation at the end of its flight? Today:
Homework: 
Class
24 Monday, 11/11/19
Warm Up: None
Today:
Homework:

Class
23.5 Friday, 11/8/19
Warm Up: Suppose you're standing motionless on a motionless skateboard on level ground, and you want to travel (with the skateboard) in a direction parallel to the skateboard's length. If you are not allowed to touch anything except the skateboard...
1. Why is this a somewhat tricky task? 2. How can you accomplish the task? 3. Explain the physics behind why your method works.
Today:
Homework: Study for the test. What's on the test

Class
23 Thursday, 11/7/19
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?
Today:
Homework:

Class
22.5 Wednesday, 11/6/19
Warm Up: Water rocket thrust = 2PA, where P = gauge pressure and A = nozzle crosssectional area. 100psi = 689,500pascals = 689,500N/m^{2} 2Liter Bottle Neck diameter = 0.022m Nozzle crosssectional area (A) = pi*(0.022m/2)^2 = 3.8*10^{4}m^{2} Water Rocket Thrust = 2PA = 2 (689,500N/m^{2})(3.8*10^{4}m^{2}) = 524N Factoring a "Nozzle Loss Factor" of 0.16, thrust = 524N*0.84 = 440N
1. If thrust depends solely on pressure and nozzle diameter, why does the amount of water in the rocket matter? What is the optimal amount of water, and why is it the best? 2. If you check your car tire pressure, and the gauge reads 40psi, what is the actual pressure in the tire? 3. Why is rocket thrust 2PA, rather than PA? If you want a more complete explanation regarding why thrust =2PA, read this. Today:
Homework:

Class
22 Tuesday, 11/5/19
Warm Up: 1. How many 100 psi water bottles would it take to launch a human?
Today:
Homework: Optional  work on problem number 11, from the rocket analysis. 
Class
21.67 Monday, 11/4/19
Warm Up: None Today:
Homework: None 
Class
21.33 Thursday, 10/31/19
Warm Up: In the diagram on the right, the tension in the rope can be found by analyzing either mass. Rope tension = m_{1}(g+a) = m_{2}(g+a). How can this be true if m_{2}>m_{1}?
Today:
Homework: Use your completed trajectory spreadsheet to find the minimum speed and optimal angle for this most efficient home run... What is the minimum speed at which a baseball must leave a bat in order to reach the fence (in the air) 340 feet away? What is the angle for this hit? Assume that the density of the air is 1.22kg/m^{3}, the mass of the baseball is 0.145kg, the circumference of the ball is 0.23m, and the ball's drag coefficient is 0.45. You may also assume that the fence is short, with a height equal to the point of contact between the ball and the bat. Video help 
Classes
20, 20.5, 21 10/2810/30
Complete all of the following before class on Thursday.

Class
19.5 Friday,
10/25/19 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 an elevator, and the elevator suddenly began to accelerate downward at 1g? 4. What is the source of the "butterflies in the stomach" when we fall?
Today:
Homework: 
Class
19 Thursday,
10/24/19 Warm Up: 1. This chicken weather vane is supposed to point into the wind. It points the wrong way. Describe two ways to fix it. 2. Why are hammers tricky to throw and catch? Provide either the simple, superficial explanation or the complex explanation behind it. CM and Rotation 3. A very light water rocket with no fins flies like a whiffle ball, but with less stablility. It can be improved by adding fins and some weights. Where should the fins and weights be added, and why?
Today:
Homework:

Class
18.5 Wednesday,
10/23/19 Warm Up: 1. Consider the 3kg mass. What does the magnitude of T_{2} need to be in order for the 3kg mass to accelerate upward? 2. Consider the 2kg mass. What relationship do T_{1} and T_{2} need to have in order for the 2kg mass to accelerate downward? 3. Consider the string between the 2kg and 3kg masses. What forces are acting on the string, and what conditions are necessary for the string to accelerate downward?
Today:
Homework:

Class
18 Tuesday,
10/22/19 Warm Up: None
Today:
Homework:

Class
17.5 Monday,
10/21/19 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. When does a falling cat experience zero net force? 2. When is a falling cat a "freefalling" cat? 3. When does a falling cat experience maximum net force?
Today:
Online Textbook (OpenStax) Reading:
Homework:

Class
17 Tuesday,
10/15/19 Warm Up: Is it literally possible to "pull yourself up by your own bootstraps?" Explain. Today:
Online Textbook (OpenStax) Reading:
Homework:

Class
16.5 Monday,
10/14/19 Warm Up: 1. If a Wiffle® Ball has a mass of about 45g, what is the upper limit of the amount of force a thrower can apply to a Wiffle Ball during the throw? 2. Why is there a limit to how much force can be applied to a thrown Wiffle Ball, no matter how strong the thrower is? 3. Describe the physical characteristics of the person who could apply the most force to the Whiffle Ball by throwing it. Who can throw a paper airplane the farthest?
Today:
Online Textbook (OpenStax) Reading:
Homework:

Class
16 Friday,
10/11/19 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 F_{net} = ma. Why is it okay to use this formula to calculate the force of gravity on an object that's sitting still (i.e. not accelerating)? 3. What would the scale read, in the diagram on the right?
Today:
Online Textbook (OpenStax) Reading:
Homework:

Class
15.5 Thursday,
10/10/19 Warm Up: What if I put a large rock on my head, with a 2"x4" on top of the rock, and then I have someone hammer a large nail through the 2"x4"? Is this a good idea? Today:
Online Textbook (OpenStax) Reading:
Homework:

Class
15 Tuesday,
10/9/19 Warm Up: Test today

Class
14.5 Tuesday,
10/8/19 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:
Online Textbook (OpenStax) Reading:
Homework:

Class
14 Monday,
10/7/19 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 Wednesday's test, memorize this or be able to calculate it based on a known conversion.
Today:
Online Textbook (OpenStax) Reading:
Homework:

Class
13.5 Friday,
10/4/19 Warm Up: What advice would you give next year's students, regarding preparation for this competition? Add suggestions to this Google Doc.
Today:
Homework: 
Class
13 Thursday,
10/3/19 Warm Up: Projectile competition Today: Homework:

Class
12.5 Wednesday,
10/2/19 Warm Up: In the competition you will get two shots at each target. Suppose your first shot goes 40cm too far. How will determine the amount of launcher adjustment that is best for your next shot? my spreadsheet Today:
Homework:

Class
12 Monday,
9/30/19 Warm Up: 1. Due to the potential destructiveness of our new projectiles, the maximum contest muzzle velocity has been reduced to 8m/s. How can you use a horizontal launch from a stool to determine whether or not your launcher's muzzle velocity has reached this velocity? 2. Instead of calibrating with a horizontal launch, you might want to have one or two degrees of launch angle. Why? 3. Projectile contest problems may require shooting projectiles at any angle between horizontal and 70 degrees above horizontal. How can you precisely measure, control, and maintain the angle of your projectile launcher? 4. How can you customize your current spreadsheet to facilitate solving the launcher problems?
Today: Main focus for today, Wednesday, and Thursday: avoid damaging anything with steel balls!!!
Coming Up:
Homework:

Class
11.5 Friday,
9/27/19 Warm Up: 1.Does drag present a problem for our projectile launchers? 2. How can we answer this question? Our spreadsheet Spreadsheet with drag Today: Coming Up:
Homework:

Class
11 Thursday,
9/26/19 Warm Up: None  test retake day Today:
Coming Up:
Homework: 
Class
10.5 Wednesday,
9/25/19 Warm Up: 1. Drawing from our growing arsenal of kinematics formulas, derive a specific formula for calculating the initial velocity (v_{o}) 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. 2. Given the same initial velocity, how will the range of a projectile launched at 80 degrees compare to the range of a projectile launched at 10 degrees? (assume a symmetric flight path)
Today:
Homework:

Class
10 Tuesday,
9/24/19 Warm Up: 1. Based on the diagram to the right, provide definitions for precision and accuracy. Which is easier to fix? 2. What does muzzle speed mean? 3. In our upcoming projectile contest, your launcher must be able to fire projectiles at muzzle speeds between 4m/s and 10m/s. If your launcher has a maximum muzzle speed of 11m/s, and your friend's has a maximum muzzle speed of 20m/s, whose launcher is more precise? Why? 4. Suppose you want to use your spreadsheet to find the muzzle velocity of a projectile launcher. What is the most precise method you can think of? Today:
Homework:

Class
9.5 Monday,
9/23/19 Warm Up: Use your spreadsheet to answer this question... Suppose you launch a projectile from the top of a tall building (80m above ground level), at an upward angle of 62 degrees and with an initial velocity of 40m/s. answers 1. How long will the projectile remain in the air before hitting the ground? 2. What maximum height will the projectile attain? 3. How far, horizontally, will the projectile travel? Today:
Homework:

Class
9 Friday,
9/20/19 Warm Up: 1. The pilot of a small plane is navigating by pointing her plane directly southward while maintaining an air speed of 100m/s. If the plane has an actual eastward velocity of 50m/s, sketch a velocity vector representing the air velocity. To eliminate some calculations, you can describe the wind velocity by providing its two component vectors. 2. If there were no windshield, and the propeller were momentarily removed, would the pilot feel air blowing from straight ahead or from some other direction?
Today:
Homework:

Class 8.5
Thursday,
9/18/19 Warm Up: Identify the component and resultant vectors for the following "river problems." Then sketch them using headtotail vector addition. 1. 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? 2. 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? 3. 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 it's 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:

Class 8 Wednesday,
9/18/19 Warm Up: No warmup. Test day
Today:
Homework:

Class
7.5 Tuesday,
9/17/19 Warm Up: Two canoe paddlers begin at the starting point in the diagram on the right. They paddle with a constant water speed. Paddler A keeps the canoe pointed westward while paddler B keeps the canoe pointed at the small island. 1. What do you think is the difference between water speed and speed? 2. Which paddler is following a heading? 3. Describe the shape of the path followed by each paddler. 4. Now suppose we increase the scale of the problem, and we remove the current. Paddler A again gets a compass, but only at the beginning of her journey. She points her canoe westward, begins traveling in that direction, and maintains her speed in a perfectly straight path (except for curving around the Earth). Assuming that her path is perfectly straight, why will she end up South of the island, regardless of her hemisphere?
Today:
Homework:

Class
7 Monday,
9/15/19 Warm Up: 1. Suppose the two vectors on the right represent two forces acting on the clam. In what direction will the clam accelerate? What will be the magnitude of the net force accelerating the clam in that direction? 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. 3. Sketch acceleration graphs for these events... my answers a. A pitcher throws a fastball to a batter, and the batter hits a line drive that is caught by the pitcher. Sketch a graph of the ball's acceleration, assuming the pitch is moving forward. b. A large, airfilled latex balloon is dropped from a height of 20 feet. The balloon hits a tile floor, bounces upward, and stops at some maximum height. c. A pedestrian is walking to our right at a constant pace. As she does this, she swings her arms normally. Graph the horizontal acceleration of her right hand, beginning at the moment her left foot touches the ground and ending three steps later.
Today:
Homework:

Class 6.5
Friday,
9/13/19 Warm Up: List all of the kinematics formulas that we have been using 1. v_{ave} = 2. v_{ave} = 3. v_{final} = 4. a = 5. displacement = 6. (v_{final})^{2} =
Today:
Homework:

Class 6
Thursday,
9/12/19 Warm Up: 1. What kinematic information can we get by calculaing the area "under" the curve of a velocity vs. time graph? 2. What does the area under the curve of an acceleration vs. time graph tell us? 3. Does the area under the curve of a position graph tell us anything? 4. Suppose we graph the acceleration of a blowgun dart that is shot across the room, sticking to the opposite wall. How can #2, above, help us draw that graph?
Today:
Homework:

Class 5.5
Wednesday,
9/11/19 Warm Up: What would the graphs look like if you graphed acceleration for these events? My answers 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.]
Today:
Homework: Finish the extended problems, if you haven't already finished them. 
Class
5 Tuesday,
9/10/19 Warm Up: 1. A race car is traveling counterclockwise around a circular track. The car's speedometer stays on exactly 100mph the whole time. Describe what happens to each of the following as the car makes one revolution around the track: a) the car's speed b) the car's velocity c) the car's acceleration. 2. How would you use dimensional analysis to convert 4m/s to mph? Mathematically speaking, why does dimensional analysis work?
Today:
Homework:

Class
4.5 Monday,
9/9/19 Warm Up: Match each position vs. time graph with the correct velocity and acceleration graph. Today:
Homework:

Class
4 Friday,
9/6/19 Warm Up: A ball is launched directly upward from the Earth's surface. The ball returns to Earth and hits the ground after a time of 10 seconds. Assuming no air resistance and g≈10m/s^{2}, fill in the values in the diagram on the right. [Though the diagram appears to show horizontal motion, assume that there is none.] Today:
Homework:

Class
3.5 Thursday,
9/5/19 Warm Up: The symbol "g" usually represents the absolute value of the acceleration of gravity near Earth's surface (in the absence of air resistance). The approximate value of g is 9.8m/s^{2}, but the acceleration of objects due to gravity is 9.8m/s^{2}.
For simplicity, use g = 10m/s^{2} to complete these motion graphs for an object with v_{0} = 20m/s and y_{0} = 0m. [Ignore air resistance.] Today:
Homework:

Class
3 Wednesday,
9/4/19 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:

Class
2.5 Tuesday,
9/3/19 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 were the approximate maximum and minimum speeds 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
2 Friday,
8/30/19 Warm Up: Use the velocity vs time graph on the right to sketch the shape of a corresponding position vs time graph. [Hint: positive velocity corresponds to movement away from a motion sensor.] Today:
Handouts: Homework:

Class
1.5 Thursday,
8/29/19 Warm Up: For each letter, describe what is happening to the person's speed and direction during the 10 seconds represented on the graph. Today:
\Online Textbook Reading: Homework:

Class
1: Wednesday,
8/28/19 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? Today:
Handouts: Online Textbook Reading: Homework:
