Class
43.5 Friday,
1/21/22 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:

Class
43 Thursday,
1/20/22 Warm Up: Let's actually solve the warmup problem from yesterday. Today:
Homework:

Class 42.5 Wednesday,
1/19/22 Warm Up: When the two blocks collide, they stick together. What is the shared velocity of the two blocks after the collision? Today:
Homework:

Class 41.5 Friday,
1/7/22 Warm Up: A student wants to launch a pencil as far as possible using energy stored in exactly two rubber bands. The sharpened pencil has fins on its eraser end and a protruding paper clip attached near the nose. The pencil is to be launched by a looped string that connects to the paper clip on one end and the rubber bands on the other. If the teacher has placed a limit on the total amount of force that can be used in launching process, would any one of these configurations be better than the others? Explain. Today:
Homework:

Class 41 Thursday,
1/6/22 Warm Up: None Today:
Homework:

Class 40.5 Wednesday,
1/5/22 Warm Up: What is an algorithm? Today:
Homework:

Class 40 Tuesday,
1/4/22 Warm Up: 1. List all of the variables that show up in kinematics problems. 2. List all of the kinematics formulas. 3. In projectile motion problems, which Today:
Homework:

Class
39.5 Monday,
1/3/22 Warm Up: 1. How would you find the efficiency of this trebuchet? 2. How can you find the center of mass of an irregularly shaped object like the one below?
Today: Determine your trebuchet's efficiency. Make a slideshow (like this one) showing your process.
Homework:

Class
39 Wednesday,
12/22/21 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. 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:
Homework:

Class
38.5 Tuesday,
12/21/21 Warm Up: Let's discuss the Midterm. Today:
Homework:

Class
38 Monday,
12/20/21 Warm Up: None Today:
Homework:

Class
37.5 Friday,
12/17/21 Warm Up: 1. How does a hydraulic lift facilitate work with a small input force and a large output force? 2. How do gears work in a car with a manual transmission? Today:
Homework:

Class
37 Thursday,
12/16/21 Warm Up: 1. What is the point of having a variety of gears on a bicycle? (or a car, motorcycle, etc.) 2. Why is this effective? Today:
Homework:

Class
36.5 Wednesday,
12/15/21 Warm Up: Click this link and answer the trebuchet question for our Physics PLC. Today:
Homework:

Class
36 Tuesday,
12/14/21 Warm Up: None Today:
Homework:

Class
35.5 Monday,
12/13/21 Warm Up: 1. Which arm ( shown in yellow, in figure 1) will wobble the least on the axle? Why? 2. Which arm (figure 2) will experience the least friction as it rotates? Why? 3. Which arm (figure 3) is least likely to bend the axle? Why? WhicToday:
Homework:

Class
35.5 Friday,
12/10/21 Warm Up: 1. Is tension the same in all parts of the slinky on the right? 2. What happens when you suspend a slinky (as shown in the photo on the right) and then drop it? 3. Why?
Today:
Homework:

Class
34.5 Thursday,
12/9/21 Warm Up: How could we measure the efficiency of this trebuchet?
Today:
Homework:

Class
34 Wednesday,
12/8/21 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 before coming to rest?
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:
Homework: Complete the problem section of Mr. Pennington's 20152016 Test on p. 1415 of the packet. Solutions 
Class
33.5 Tuesday,
12/7/21 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. 1. Which "machine" is fundamentally different? Why? If you don't have a quick answer to this, move on to the other questions and come back to this one. 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: Complete the multiple choice section of Mr. Pennington's 20152016 Test on p. 1113 of the packet. Solutions 
Class
33 Monday,
12/6/21 Warm Up: Suppose I hang a spring from the ceiling. I then hook a 200g mass to the bottom end of the spring and let go. The mass falls and bobs up and down until it finally comes to rest. The spring's constant is k = 4N/m. 1. Does the spring have more total energy at its low point or at its final resting point? 2. How much work is done by friction during the time the weight is bobbing?
Today:
Homework: Complete the rest of packet p.910 (#411, "More work and energy practice problems") solutions Video explanations 
Class
32.5 Friday,
12/3/21 Warm Up: Assuming that all three bows are drawn to a distance of 0.5m... 1. Which bow stores the most energy when it is drawn to this distance? 2. Estimate the energy stored in each bow. Today:
Homework: Two parts!

Class
32 Thursday,
12/2/21 Warm Up: 1. Can you guess what the "sisyphus train" does? 2. How did it get that nickname?
Today:
Homework: Complete page 5 of the packet. Solutions Video for problem 1 (#1 of the practice quiz) 
Class
31.5 Wednesday,
12/1/21 Warm Up: What will happen to kinetic energy, potential energy, thermal energy, and total energy of the skateboarder during a ride in the half pipe? A) with zero friction B) with a lot of friction Today:
Homework: None 
Class
31 Tuesday,
11/30/21 Warm Up: No warm up  test today Today:
Homework:

Class
30.5 Monday,
11/29/21 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:
Homework:

Class
30 Friday,
11/19/21 Warm Up: None Today:
Homework:

Class
29.5 Thursday,
11/18/21 Warm Up: Why does tension show up so often in physics problems? Is tension overrated and overrepresented? Today:
Homework:

Class
29 Wednesday,
11/17/21 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 using the headtotail method? [Let's just assume that the bone is frictionless.]Today:
Homework:

Class
28.5 Tuesday,
11/16/21 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
28 Monday,
11/15/21 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
27.5 Friday,
11/12/21 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:
Homework:

Class
27 Thursday,
11/11/21 Warm Up: None Today:
Homework:

Class
26.5 Wednesday,
11/10/21 Warm Up: The 50kg rower in the photo is accelerating at a rate of 1m/s^{2}. She is pulling against the oars with a force of 100N. Calculate and show all of the forces acting on the rower. Today:
Homework:

Class
26 Tuesday,
11/9/21 Warm Up: This is a graph of one group's "pressure altitude" data. The graph shows altitude vs "elapsed seconds." What do you notice? Can you explain any of its oddities? Today:
Homework:

Class
25.5 Monday,
11/8/21 Warm Up: How many water bottles are used to launch this game show contestant? Is this for real?
Today:
Homework:

Class
25 Friday,
11/5/21 Warm Up: None  rocket launch Today:
Homework:

Class
24.5 Thursday,
11/4/21 Warm Up: The graph on the right shows the current acceleration data for the PocketLab sensor sitting motionless on my desk. The positive Z axis (green) extends "perpendicularly" out of my desk surface. The positive X axis (orange) extends rightward from the sensor. The positive Y (purple) axis extends away from the camera, parallel to the desk surface.
Why are the X and Y axes showing a constant acceleration near 0m/s^2, while the Z axis shows a constant acceleration of around positive 1g?
Today:
Homework:

Class
24Wednesday,
11/3/21 Warm Up: No warmup today. Make rockets.
Today:
Homework:

Class
23.5 Tuesday,
11/2/21 Warm Up: [Video link for absent students]The diagram on the right shows a typical water rocket. Mass has been added to the tip of the rocket, and fins have been added to the back (bottom). There is a requisite 10cm long section dedicated to holding foam for protecting the probe. 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?
Today:
Homework:

Class
23 Monday,
11/1/21 Warm Up: Starting from rest, a car in the real world (which includes air) accelerates to its maximum speed, maintains that speed for a few seconds, and then brakes as rapidly as possible. Draw a series of four force diagrams to 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 time periods. Draw a diagram for... 1. The car at rest 2. The car undergoing initial acceleration 3. The car at maximum velocity 4. The car braking Today:
Homework:

Class
22.5 Friday,
10/29/21 Warm Up: 1. Which can you throw with more force, a Wiffle Ball® (0.045kg), a baseball (0.145kg), or a shot put (5.45kg)? Or is there no difference? Explain your thinking. Some calculations  don't peek before thinking. 2. What limits the amount of force that you can apply when you throw an object? Interesting Link: article about the fastest pitch ever thrown
Today:
Homework:

Class
22 Thursday,
10/28/21 Warm Up: 1. How does NASA simulate weightlessness? 2. You are trying to transfer some drippy sauce across a dinner table using only a drippy spoon. The sauce needs to go from the pot to your plate without dripping. Touching only the spoon, how can you make this happen? 3. What would happen if you were standing on a bathroom scale in a motionless elevator, and then the elevator suddenly began to accelerate downward at 1g? 4. What is the source of the "butterflies in the stomach" when we fall?
Today:
Homework:

Class
21.5 Wednesday,
10/27/21 Warm Up: How fast does chalk fall? My spreadsheet answer Today:
Homework:

Class
21 Tuesday,
10/26/21 Warm Up: A parachuter steps out of a plane. The total mass of the parachuter and gear is 100kg. After falling for a while, the parachuter reaches a terminal velocity of 55m/s. A short time later, the parachuter pulls the chute cord and reaches a new terminal velocity of 3m/s. From that point in time, the parachuter continues to drift to the ground.
Today:
Homework:

Class
20.5 Monday,
10/25/21 Warm Up: According to this article, emergency clinic records of 132 cats that jumped from windows of buildings showed a 90% survival rate. The average drop was 5.5 floors.
Injuries increased with increasing heights up to 7 floors.
When cats fell from over 7 floors, they actually suffered from
“less injuries.”
1. What's going on? 2. What's the rule for deciding whether to use "less" or "fewer?" Which applies here? 3. When does a falling cat experience zero net force? 4. When is a falling cat a "freefalling" cat? 5. When does a falling cat experience maximum net force?
Today:
Homework:

Class
20 Friday,
10/22/21 Warm Up: 1. Explain how a nordic skier can ski forward on level ground with parallel skis (classic style) and without using poles. 2. Can this be done with downhill skis? Explain. Today:
Homework:

Class
19.5 Thursday,
10/21/21 Warm Up: I have a length of treated 4"x4" lumber, some large nails, a hammer, and a large rock. How will it feel if I put the rock on my head and then have someone pound nails into the wood on top of the rock? Today:
Homework:

Class
19 Wednesday,
10/20/21 Warm Up: None  retake day Today:
Homework: (continued from yesterday)

Class
18.5 Tuesday,
10/19/21 Warm Up: On level ground, Tim begins sliding with a velocity of 6m/s. If Tim's slide lasts for 2 seconds, what is the coefficient of kinetic friction between Tim and the slide? Today:
Coming up:
Homework: Due on Thursday!

Class
18 Monday,
10/18/21 Warm Up: One way to find the center of mass (a.k.a. balance point) of a stick is to support it with two hands and then slowly move those two hands together until they meet under the stick's center of mass. Why does this method work? Today:
Coming up:
Homework:

Class
17.5 Friday,
10/15/21 Warm Up: Why can't you literally "pull yourself up by your own bootstraps?" This question has also been stated as "why can't you pick yourself up?" Today:
Homework:

Class
17 Thursday,
10/14/21 Warm Up: It is possible to remove a sheet paper from under a dry erase pen without touching or tipping the pen. How can one do this without tipping the pen? Why does the pen usually fall? Today:
Homework:

Class
16.5 Wednesday,
10/13/21 Warm Up: There is a heavy object suspended from the ceiling by a string. Another segment of the same string is hanging downward from the object. I am going to pull on the bottom string until one of the two strings breaks. Which string is going to break first? Why? Today:
Homework:

Class
16 Tuesday,
10/12/21 Warm Up: Get your launchers ready. No practice shots! Make a plan. Once we get going, we need to achieve less than one minute per shot. The first shooters can have a little extra time. Today:
Homework:

Class
15.5 Thursday,
10/7/21 Warm Up: None Today:
Homework:

Class
15 Wednesday,
10/6/21 Warm Up: None Today:
Homework:

Class
14.5 Tuesday,
10/5/21 Warm Up: A boat is following a heading of 56 degrees N of E, and its speed in still water is 1.3 m/s. Find the velocity of the river's current if the boat's actual velocity (relative to the Earth) is 3.2m/s in a direction 17 degrees W of N. Solution... Video explanation Today:
Homework:

Class
14 Monday,
10/4/21 Warm Up: Final launcher considerations... 1. How are you going to aim your launcher in the horizontal plane? 2. How are you going to aim your launcher in the vertical plane? 3. How are you going to decide on your projectile's initial height? [Remember that you will be given a vertical "launch window," and it is up to you to determine the exact launch height.] 4. How are you going to hold your launcher steady, at the height and angle of your choice? 5. What are you going to do if you take a test shot and it turns out that your distance is off by a large amount? Today:
Homework:

Class
13.5 Friday,
10/1/21 Warm Up: Let's try out the PhET Projectile Motion Simulation and see what it has to offer. The riverboat simulator is also interesting, but I would change the wording a bit. Can you guess what I would change?
Other Stuff
Homework:

Class
13 Thursday,
9/30/21 Warm Up: What's the best way to create a graph like this one? Exactly what do you need to do? Today:
Homework:

Class
12.5 Wednesday,
9/29/21 Warm Up: I like to start projectile problems by listing important variables in the X and Y dimensions (x and y components of motion). It might also be helpful to list some resultant variables. Let's try. Today:
Homework:

Class
12 Tuesday,
9/28/21 Warm Up: 1. Based on the diagram to the right, provide definitions for precision and accuracy. Which is easier to fix? 2. Can you suggest some ways to improve precision? Accuracy? 3. What are some probable sources of error in your attempts to hit the target?
Today:
Homework:

Class
11.5 Monday,
9/27/21 Warm Up: The diagram on the right shows the trajectory of a freefalling projectile that was launched horizontally. Sketch the diagram. Show/label the projectile's overall velocity (v), x velocity (v_{x}), and y velocity (v_{y}) at the start of its flight and at some other point in the flight. Today:
Homework: Finish any homework that you didn't complete for last class (including the projectile launcher practice problems  p. 15; and Mr. Pennington's practice test  p. 1015)

Class
11 Friday,
9/24/21 Warm Up: None  test retake day Today:
Homework:

Class
10.5 Thursday,
9/23/21 Warm Up: Find a combination of initial angle and initial speed that will carry a projectile from the launch point to the target (assuming no air resistance). You can guess, and I will check, with my private spreadsheet. :) Today:
Homework:

Class
10 Wednesday,
9/22/21 Warm Up: 1. Based on the existing pattern, what should number should appear in the 7th row of column C? 2. If we wanted to continue that pattern quickly and easily, how could we set up a spreadsheet to do it?
Today:
Homework:

Class
9.5 Tuesday,
9/21/21 Warm Up: Sketch a headtotail diagram for each of the following. We will look at the graphical solutions afterward. 1. A baggage conveyor is moving in a direction 25 degrees South of East at a rate of 1.5m/s. A bug riding on the conveyor has a velocity of 2m/s in a direction 30 degrees East of South. What is the bug's heading and "speed on a still conveyor?" 2. A river's 3mph current flows in a direction 15 degrees West of North. A swimmer, whose speed in still water is 2m/s, swims across the river with a heading 35 degrees South of West. What is the swimmer's velocity, relative to the Earth? 3. A superhero steward on an airplane is traveling in a direction 10 degrees East of South, and their speed is 580mph. The plane's velocity is 460mph in a direction 5 degrees West of South. What is the steward's heading and their "speed on a still plane?"
Sketches and answers: Argh!! #1 is wrong! But 2 and 3 are right.
Today:
Homework:

Class
9 Monday,
9/19/21 Warm Up: Suppose you shoot a projectile, horizontally, from the edge of a school tabletop that is 0.95m above the floor. If the projectile hits the floor at a distance of 14 floor tiles from the table... a. What is the projectile's v_{0}? b. How would you find the projectiles' final speed? c. How would you find the angle at which the projectile hits the floor?
Today:
Rest of the week (tentative plan):
Homework:

Class
8.5 Friday,
9/17/21 Warm Up: 1. What do "air speed" and "speed in still water" mean? 2. What is a "heading?" 3. Let's practice resolving nonorthogonal vectors into their x and y components. Identify the component and resultant vectors for the following "river problems." Then sketch them using headtotail vector addition. 3. A boat travels eastward at a rate of 3m/s. The boat's heading is northeastward, and the boat's speed in still water is 8m/s. What is the velocity of the water in which the paddler is paddling? 4. A quadcopter has a velocity of 20m/s westward. The wind is blowing southward at a rate of 10m/s. What are the quadcopter's airspeed and heading? 5. The driver of a golf cart on an aircraft carrier uses a compass to head northward. The cart's speedometer reads 10mph. The aircraft carrier's heading is eastward, and its speed in still water is15mph. The ocean current is northwestward at a rate of 5mph. What is the actual velocity (relative to the Earth) of the golf cart?
Today:
Homework:

Class
8 Thursday,
9/16/21 Warm Up: An airplane flying horizontally with a ground speed of 120 m/s releases care packages from a height of 4,800 meters. If the packages are not affected by air resistance, how far ahead of the target (in the x dimension) should the packages be released?
Today:
Homework:

Class
7.5 Wednesday,
9/15/21 Warm Up: 1. Suppose the two vectors on the right represent two forces acting on the clam. In what direction will the clam accelerate? How will that acceleration compare to the accelerations we would observe if each force were acting alone? 2. The diagram on the right shows a top view of a train car that is moving at a rate of 2m/s. You are in the car. In which direction and how fast should you walk in order to have the intended velocity shown on the right.
Today:
Homework:

Class
7 Tuesday,
9/14/21 Warm Up: None Today:
Homework:

Class
6.5 Monday,
9/13/21 Warm Up: How can we find the acceleration of an object as it slides across this floor, using only a stopwatch and the floor as measuring devices? Today:
If you could travel in time, and if you found yourself in the infinite loop of acceleration changes shown below... would you ever find yourself in the same location as another past self? Explain by creating analagous graphs of velocity and distance vs time. Homework:

Class
6 Friday,
9/10/21 Warm Up: 1. Create a kinematics problems (on your own, or as a class). Start by listing the available formulas and/or variable. 2. If we graphed the motion of a verticallylaunched projectile, which of these graphs would have at least one sharp corner in it? a. velocity vs. time b. speed vs. time c. position vs. time d. acceleration vs. time e. none of these f. all of these Today:
More Kinematics Practice (optional!)
Homework:

Class
5.5 Thursday,
9/9/21 Warm Up: Sketch a graph of acceleration vs. time for a suction cup Nerf dart that is shot at a wall. Start your graph just before the dart begins to move, and end it just after the dart stops. Today:
Homework:

Class
5 Wednesday,
9/8/21 Warm Up: Mr. Chase pointed out that there are 9 types of motion. This is based on the fact that Velocity can be +, , or 0, and acceleration can also be +, , or 0. A pendulum swinging back and forth demonstrates 8 out of these 9 types of motion. 1. Graph the pendulum's X velocity over one full period (over and back) of motion. 2. Identify where in the video each of those 8 types of motion occurs. 3. Which of these 9 types of motion is not demonstrated?
Today:
Homework:

Class
4.5 Tuesday,
9/7/21 Warm Up: Simplify this "extended" kinematics problem by drawing a diagram and identifying intervals with unique accelerations and or unique initial/final conditions. You don't have to solve the problem. A ball is dropped (in freefall) from a height of 16m. When it reaches a speed of 3m/s, the ball contacts a compression spring. The ball continues downward, slowing down as it compresses the spring and then speeding up as it is thrown back upward by the spring. For purposes of calculation, you can consider the ball to experience a constant +35m/s^{2} acceleration during its 0.15 seconds of contact with the spring. 1. What is the height of the ball when the spring is fully compressed? 2. What is the maximum height of the ball after it leaves the spring? Today:
Homework:

Class
4 Friday,
9/3/21 Warm Up: 1. Suppose students enter our school at a rate of 54 pounds/sec (pounds of student). After they enter, they lie down, headtotoe, forming a line whose length is the sum of their heights. Since an average 16 year old student's weight:height ratio is about 2.07 lb/in (and assuming these are all average students with that ratio), how many days will it take them to form a line 3 miles long? 2. Is this actually a "possible problem," in the sense that it could happen and that it is solvable given the information above? Today:
Homework:

Class
3.5 Thursday,
9/2/21 Warm Up: Consider the case of this ball. At t = 0s, the ball is freefalling directly upward at a height o 10m, with a speed of 20m/s. Sketch graphs of the ball's position, velocity, and acceleration (vs. time) over the next 4 seconds. [For simplicity, use g =10m/s^{2} instead of g = 9.8m/s^{2}] Today:
Homework:

Class
3 Wednesday,
9/1/21 Warm Up: 1. For letter a, on the right describe what an object could be doing in order to have both positive velocity and positive acceleration. 2. Do the same for the rest of the letters.
Today:
Homework:

Class
2.5 Tuesday,
8/31/21 Warm Up: What is a spool tractor? How does one work? Today:
Homework:

Class
2 Monday,
8/30/21 Warm Up: 1. Assuming that the man in the picture is 2m tall, and the frame rate of the camera was the usual 30 frames per second, what was the approximate maximum speed of the object? 2. Based on your answers, do you think the assumption of 30 frames per second was too low, too high, or about right? Today:
Homework:

Class
1.5 Friday,
8/27/21 Warm Up: Use the velocity vs time graph on the right to sketch the shape of a corresponding position vs time graph. [Assume that motion away from the sensor is positive, and motion toward the sensor is negative.] Today:
Optional Reading  Online Textbook: Homework:

Class 1:
Thursday,
8/26/21 Warm Up: Suppose you're involved in a 2 lap race. If you want your overall average speed to be twice as fast as your speed for the first lap, how much faster do you have to go during the 2nd lap? [To calculate average speed you can use rate = distance / time] Today:
Optional Online Textbook Reading: Homework:

Class
0.5: Wednesday,
8/25/21 Physics 200: Mr. Stapleton Warm Up: Spin one of the "sprotating cylinders" by pressing one end until it squirts out from under your finger. Try pressing the other end. When the cylinder is spinning, why do you only see the symbol that you press? Today:
Links:
Online Textbook Reading: Homework: None 