Week 1
Welcome to General College Physics at Wisconsin Lutheran High School! The sidebar (to the right) has some basic information about this course, such as the Professor's contact information and the textbook we will be using. You might wish to take a look at that first.
Reading: PSE Chap 1, Physics and Measurement
...see more info for this week.
Reading: PSE Chap 1, Physics and Measurement
...see more info for this week.
Week 3
Topics: Estimation, displacement, velocity, acceleration, free fall
No Quiz this week.
Week 3 exercises:
Classroom problems: As a reminder, these are some of the problems we worked out in class…
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:
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.
- 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 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.
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 9
Reading: PSE Chap 6, Circular motion and other applications of Newton's laws
...see more info for this week.
...see more info for this week.
Week 13
Topics: angular velocity, angular acceleration, rotational kinematics
Quiz on Monday.
Week 13 exercises:
Quiz on Monday.
Week 13 exercises:
- Rotating record player: Consider a record player. The record, in the form of a disk, spins at a rate of 33 revolutions per minute. A small bug of mass m = 1 gram is located 10 cm from the axle; it clings tenaciously to the record as it spins. (a) What is the period of revolution, T, of the record, in seconds.(b) What is the frequency of revolutions, f, in Hz. (c) What is the angular speed, omega, in radians per second. (d) If, at time t = 0, the bug is located at an angle theta = 0, then through what angle has the bug moved in one second? Report this in both radians and in degrees. (e) Is the bug accelerating as it clings to the record player? If so, then what is the magnitude and direction of the acceleration?
- Slowing record player: Suppose now that the record player to which the bug is clinging, which is initially turning at 33 rpm, is turned off. It decelerates at a constant rate until it comes to a stop 10 seconds later. (a) What is the angular deceleration, alpha, of the record player (in radians per second squared)? (b) Make a plot of the angular speed as a function of time. Appropriately label your plot. (c) What is the angular speed, omega (in radians per second), of the record player at t = 5 seconds? (d) What is the speed of the bug at this moment in time? (e) What is the acceleration of the bug at this moment in time? In particular, what are the magnitude and directions of both the centripetal and tangential acceleration of the bug at this moment? (f) What is the magnitude of the frictional force acting on the bug at this moment?
Week 14
Topics: torque, rotational inertia, rotational dynamics.
Quiz on Monday.
Week 14 exercises:
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?