Spring 17 Mechanics Week 2


Before Class
What if you want to see a video the second time and also want to see the questions? Just click on the small vertical bars at the bottom of the video that indicate where the questions are located in the video.

  1. View Pushing Box Problem.
  2. View this 3 minute video : Energy, Work, and Power. Be prepared to answer this question: a 1000 kg car starts from rest and accelerates to 30 m/s in 5 seconds. Please calculate the average power the car produces to do this. Please put answer in Watts and Horsepower.
  3. Read

During Class

Prepare for your activity Wednesday.


We are going to graph some of our own motion Wednesday. I show you how I did it in #3 below. #2 is a super cool way to do it (in my opinion), but some students had difficulty getting the software to work.

Before Class. Please watch the following videos:

  1. Please view the video kinematic graphs, LIVE! and watch me draw graphs on a board to represent my motion on a bicycle.
  2. View Smarter Every Day Grasshoppers, and try to repeat his experiment with the other grasshopper. You may have an easy time doing this, or you may have great difficulty because of software compatibility. A past student wrote this to help tracker instructions. Please work together. In the face of fighting with malicious software, you need good friends. All the same, if it doesn’t work for you, please do your best to estimate the acceleration using my Excel method in the graphing video I did below. One student was able to get tracker to work on a Mac only after transforming the video into a .mov… here it is Grasshopper .mov
  3. I graphed my motion without Tracker. Please view: Graphing running
  4. See a video about how to measure power.
  5. Wednesday, we’re going to meet at Via Carta to take videos of us to calculate kinematics, forces, energy, power, and look at momentum conservation. The first project description link is on the main class webpage. Please take a look at it.
  6. Readings:
  7. PS#2 is posted on main class website. Please see.

During Class
Warm up problems,
Practice and prepare for activity tomorrow.

The vector sum of the Forces = mass * acceleration.
we will take an analyze data on our movement.

Before Class

  1. PS#2 is posted on main class website. Please see.
  2. Graphing a ball toss.
  3. Please see how I solved the Grasshopper Problem Using Excel.
  4. Prepare for the activity during first half of class. Review the project. The link is on the main class page.
  5. Please see PS#3, which is the same as last quarter’s first midterm.
  6. Consider adding an Environmental Studies Minor into your degree.

Environmental Studies Minor.png

During Class:
Meet at Via Carta by the lowest side of our building and record your video. Bring anything you may need.

Thursday We will explore more complicated dynamics problems.
Before Class

  1. The Elevator Dynamics Problem
  2. Please see this video demonstrating the dynamics protocol.
  3. Bozeman Science FBDs
  4. Read about dynamics protocol.
  5. Solutions to PS#1 posted

Then what is equilibrium? How do we find the resultant force? We introduce the “dynamics protocol” (Quiz on this today)

“The Protocol for Dynamics”:
0) Identify that this problem is about forces => It’s a dynamics problem
1) “I do know that (vector sum) F = ma”
2) “I need to know forces and acceleration!” Draw a force (free body) diagram labeling all the forces and acceleration (or is it in equilibrium?)
3) I can make a Vector Sum of the Forces diagram showing how the forces add to give a net force …. this net force must be in the same direction as the acceleration.
4) Define the positive direction
5) Substitute values and solve.

During Class

  • How do you keep the water in the bottom of the bucket?
  • Vector diagrams for Dynamics Problems, a string breaks.
  • Conserving momentum in the roller coaster problem.