General College Physics

Wisconsin Lutheran High School

Topics: Estimation, displacement, velocity, acceleration, free fall

No Quiz this week.

Week 3 exercises:

Orbital speed estimation: Estimate the speed of the earth as it orbits around the sun. Hint: the earth is bit under 100 million miles from the sun. Don't look up any other numbers in books or on the internet or anywhere. Remember: when estimating, round to just one significant figure. No calculators! If you have to use a calculator, you are doing it wrong.
Spiders estimation: Estimate the number of spiders inside your house. Do not look up any numbers anywhere, and explain your reasoning. And again: no calculators!
Ping pong balls estimation: Estimate the number of ping pong balls can be placed (in a single layer) on the surface of Lake Michigan? Do not look any numbers anywhere, and do not use a calculator! What quantities do you need to estimate? What assumptions must you make?
Thrown object: An object is thrown straight up wards from the ground level with a speed of 50 m/s. What is its distance from the ground 3 seconds later? Six seconds later? At what time does it strike the ground?
Dropped ball: A ball is dropped from a 100 meter cliff. Assume that the acceleration due to gravity is 10 m/s^2. (a) What is the time it takes to strike the ground? (b) What is its speed when it strikes the ground? (c) Make a graph of the ball's (i) velocity versus time, (ii) acceleration versus time and (iii) height versus time. (d) If the ball is perfectly elastic, so that its motion is reversed the moment it hits the ground, then how long will it take to get back up to 100 meters? What will be its speed at the top of its flight? What will be its acceleration at the top of its flight?

Classroom problems: As a reminder, these are some of the problems we worked out in class…

Uniform motion: how far does a car moving at 30 mph travel in 1, 2, 3 hours?
Uniform acceleration: how far does a uniformly accelerating car travel if it speeds up from 0 to 30 mph in one hour?

Week 4

Topics: One-dimensional kinematics, vector algebra

Week 4 exercises:

Accelerating object: An object starts from rest at the origin and moves along the x-axis with a constant acceleration of 4 m/s^2. What is its average velocity as it goes from x=2 to x=8 meters? Plot the position, velocity, and acceleration versus time for this object.
Accelerating car: A car, initially at rest travels 20 meters in 4 seconds along a straight line with constant acceleration. What is its acceleration? Make a plot of the position, velocity and acceleration of this car.
Accelerating truck: How far does a truck travel in 6 seconds if its initial velocity is 2 m/s and its acceleration is 2 m/s^2 in the forward direction?
Ramp laboratory experiment

Set up a ramp. Measure the angle of the ramp with respect to the horizontal desktop.
Roll a small steel ball down the ramp. Record the time the ball takes to roll 10, 20, 30, 40, etc. cm down the ramp. Be sure to record experimental uncertainty.
Repeat this procedure for at least three different ramp angles.
Make a plot of the distance (ordinate) as a function of time (abscissa) using graphical analysis software. Do a power-law fit to your data. Label your plot appropriately. Do this for each of the three ramp angles. Put the data from all three data sets on the same graph.
Using the kinematic equations we've learned this week, determine the acceleration of the ball from your graphs. How does the acceleration depend on the ramp angle? Make a plot of acceleration versus ramp angle. Does this make sense? Explain.

Classroom exercises: As a reminder, these are some of the problems we worked out in class…

Finding average velocities from displacement vs. time plots
Finding the time of flight and height of a ball thrown upwards.
1-d kinematic equations: the connection between geometry (area under velocity vs time plots), algebra (kinematic equations relating position, velocity and acceleration), and calculus (integrating acceleration to find velocity and again to find position).

Week 5

Topics: two-dimensional kinematics, projectile motion

Quiz on Monday

Week 5 exercises:

Accelerating particle: A particle's position is given by x(t) = 12 t - 3 t^2. What is v(t)? What is a(t)? Make a sketch of its position, velocity and acceleration versus time (time on the x-axis). Is the particle ever at rest? If so, when? Note: this problem uses derivatives, a method of calculus with which some of you may not (yet) be familiar.
Soccer problem: A soccer player kicks a ball with an initial speed of 4 m/s at an angle of 30 degrees above the horizontal. How much time is the ball in the air before it lands on the ground? What is the maximum height the ball reaches? What is the ball's range? What is its velocity at the top of its flight (magnitude and direction)? What is its velocity at the moment it strikes the ground? And what is its velocity at the moment it is halfway up to its maximum height?
Artillery problem (challenging): An ambitious artillery officer wishes to fire a projectile from ground level so that it goes through a small window in a distant tower. The window is 30 meters above ground level. The tower is 8 kilometers from the launch point. The gun is aimed 30 degrees above the horizontal. What must be the muzzle velocity so that the projectile goes into the window? Assume that there is no wind or other drag acting on the projectile while in flight.

Week 6

Reading: PSE Chap 4, Motion in Two dimensions
...see more info for this week.

Week 7

Reading: PSE Chap 5, The laws of motion

Deadline for registration for College Credit: You can. Receive college credit for this course from Wisconsin Lutheran College. Click on the application link below to register for each class you are wishing to apply for college credit. This must be approved by Friday, September 27.

https://admissions.wlc.edu/register/foundations

Once students apply we will wait for Wisconsin Lutheran College to confirm eligibility and requirements for college credit and communicate out further information. Please reach out to Mr. Davis if you have any questions.
...see more info for this week.

Week 8

Reading: PSE Chap 5, The laws of motion
...see more info for this week.

Week 9

Reading: PSE Chap 6, Circular motion and other applications of Newton's laws
...see more info for this week.

Week 10

Week 11

Reading: PSE Chap 8, Potential energy and conservation of energy
...see more info for this week.

Week 12

Reading: PSE Chap 9, Linear momentum and collisions
...see more info for this week.

Week 13

Reading: PSE Chap 10, Rotation of a rigid body about a fixed axis
...see more info for this week.

Week 14

Topics: torque, rotational inertia, rotational dynamics.

Quiz on Monday.

Week 14 exercises:

Rotational inertia of triangle: Three 1 kg masses are fixed at the corners of an equilateral triangle. The sides have length 2 meters. If this triangular system rotates around the center of mass of the triangle, then what is its rotational inertia?
Automobile problem: A 1500 kg automobile has a wheel base (distance between wheels) of 3 meters. The center of mass of the automobile is on at the center line at a point 1.2 meters behind the front axle. Find the force exerted by the ground on each wheel.
One mass suspended from pulley: A 10 kg mass is suspended from a thin string. The string is wrapped a bunch of times around a solid disk that acts as a pulley. The disk/pulley has a mass of 2 kg and a diameter of 5 cm. The mass is released from rest and so it begins to descend due to its weight. As it does so, the string, which is wrapped around the disk, causes the disk to rotate (the string does not slip). (a) How much torque does the 10 kg mass exert on the disk? (b) What is the angular acceleration of the pulley as the 10 kg mass falls? Is it constant? (c) What is the angular velocity of the pulley? Is it constant, or time dependent? (d) The floor is 3 meters beneath the release point of the 10 kg mass. How long does it take to hit the floor? (e) What is the speed of the mass just before it hits the floor?
Rotational inertia laboratory: This week, we will be working with a rotational inertia apparatus. The goal is to predict how much time it will take for a falling mass to strike the ground. The falling mass, however, is suspended from a string which is wrapped around a rotatable shaft.

First, carefully measure the masses on the crossbeam and their locations. From this, determine the rotational inertia of the apparatus. Be sure to include an estimate of the rotational inertia of the vertical shaft.
Now measure the mass that is to be dropped. Also, measure the distance between the mass and the floor.
Set up a free body diagram and attempt to predict the acceleration of the falling mass. Don't forget that the tension in the string is supporting it!
From the acceleration and the distance, predict the time of fall. Put a box around your prediction. Now get your instructor to come watch your falling object. Determine the percent difference between your prediction and your experimental results.
How might your experiment be done better?

Week 15

Reading: ...see more info for this week.

Week 16

Topics: Planetary motion, Kepler's laws

Quiz

Week 16 exercises:

Week 17

Reading: PSE Chap 14 gravity
...see more info for this week.

Week 18

Week 19

General College Physics

Return to course website.

Course syllabus

General College Physics is a year-long introductory college-level course for advanced (typically junior or senior level) students at Wisconsin Lutheran High School. It is a dual-credit course offered at Wisconsin Lutheran High School in collaboration with Wisconsin Lutheran College. This means that students enrolled in the course have the option of receiving credit for a four-credit algebra-based laboratory science course from the College.

During the first semester, we will primarily study the science of motion and its relationship to forces. Topics include: dimensional analysis, measurement, uncertainty, estimation, two dimensional kinematics, projectile motion, newton’s laws, force diagrams, centripetal force, circular motion, conservation of energy and momentum, torque, angular momentum, oscillations, and gravity. During the second semester, we will explore a number of inter-related topics including: heat, thermometry, the laws of thermodynamics, electricity, magnetism, optics, electromagnetic induction, radiation, atomic theory, and nuclear physics.

Emphasis on theoretical topics, careful thinking, laboratory experiments, and problem solving makes this course challenging. My aim is to help you succeed in this course, and to have fun while learning physics. So please do not hesitate to contact me with any problems you may run into this semester!

Course textbook: The course will be loosely organized around a book: the Pocket Guide to accompany Physics for Scientists and Engineers (4th edition) by Serway. (I’ll call this PSE for short.) I would highly recommend obtaining a copy of this book. It is inexpensive, compact, and well-written. It will make a very handy addition to your home science library. If you don't want to buy it, I will have copies to loan out for the semester.

Course time and location: The course meets on a rotating schedule in WLHS 223—the science wing on the first floor of WLHS.

Professor: Dr. Kuehn from Wisconsin Lutheran College (WLC) is the professor for this course. Best contact info: kerry.kuehn[at]wlc.edu

Registration for College Credit: Wisconsin Lutheran College is requiring students in this course who are interested in obtaining college credit. Please apply in the application link below for each class you are wishing to apply for college credit. This must be approved by Friday, September 27.

https://admissions.wlc.edu/register/foundations

Once students apply we will wait for Wisconsin Lutheran College to confirm eligibility and requirements for college credit and communicate out further information. Please reach out to Mr. Davis if you have any questions.

Teaching Assistants One day each week (beginning in September) the course will be overseen by teaching assistants Richard “Ricky” Hill and Henry Brown. Both are physics major enrolled at Wisconsin Lutheran College.

Course websites: In addition to the course information provided through WLHS’s OnCampus system, we will be also using a website I’ve designed for this course: www.greatphysics.com/WLHS/

Homework exercises: II will assign weekly homework problems. These are designed to deepen your understanding of lecture material and to prepare you for the quizzes and tests. Although I do not intend to regularly grade your homework solutions, I will occasionally do “spot checks” to make sure that you are keeping up with the material. I plan to give credit for submitting your best attempt by the assigned due date (typically Sunday late afternoon). Late assignments will receive reduced credit.

Laboratory exercises: Some of our weekly assignments will include laboratory work. Labs will typically take up at least two class periods. Your laboratory notebook pages must be scanned and submitted electronically as a single file by the assigned due date. More details about the required format and expectations will be discussed before the first laboratory period. You will need to order/purchase a dedicated laboratory notebook. Here are guildlines on what to include in your laboratory notebook.

Quizzes: We will have in-class quizzes almost every week on Monday. To prepare for quizzes, you should read the assigned book chapter (at least once), review the lecture material, complete all of the homework problems, and review the homework solutions.

Tests: We will have a final exam before the end of the second quarter, and a comprehensive final examination before the end of the fourth quarter.

Software: Logger Pro 3.15 Is an excellent data analysis software package. Download for Wndows 10, 8.1, 7, and for macOS 10.14, 10.13, 10.12, 10.11, 10.10. For more details on how to download and install Logger Pro click here.