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:
