Most of our time today was spent reviewing the results of the test we took on Wednesday. But then we got back to things moving in a circular path. We also received a set of problems to begin our work with objects that move with uniform circular motion (UCM).
Assignment: Giancoli Ch 5 Problems: 1, 2, 3, 5 Things go in circles. How can we account for that? Today we saw that a broom had to push a bowling ball in toward the center of the circular path of the ball was taking. The same thing was true for the cup of water we spun around. The gravitational force and the support force that was normal to the surface the cup was sitting on added up to a net force toward the center of the circular path. Our mathematical effort to find the acceleration of an object in uniform circular motion involved vectors. Assignment:
Read Sections 1 and 2 of Chapter 5 in our text for Friday. We finished our discussion of the Chapter 6 Problems today. Tomorrow we will work through the Practice Test to see if we are prepared.
Announcements:
TODAY IN CLASS We completed the presentation of Chapter 6 problems today. We will turn them in tomorrow, and I plan to get them back to you on Friday. You should begin reviewing the Chapter 6 Objectives and the Ch 6 Practice Test. We spent most of our time working on Chapter 6 problems and presenting our solutions. We also turned in our graphs relating the force exerted by a spring to the "stretch" of the spring, that is, its extra length beyond its unstretched length. The mathematical relationships that we will derive from our graph are: F is the force exerted by the spring, k is the spring constant, SPE is spring potential energy, and x is the stretch of the spring (NOT the length of the spring!).
Assignment: Chapter 6 Test will be on Wednesday, February 23. We presented our plots of spring force as a function of the "stretch" of the spring. We interpreted the slope and the "area" or integral of this plot. The slope is called the spring constant, and it tells us how many Newtons of force are required to stretch a spring 1 meter. The integral turns out to tell us how much energy is transferred to or from a spring as it changes its stretch.
Assignment: Prepare your graph to turn in tomorrow. Today we saw how to make a "chart" in Excel, Numbers (on Macs), and Google Sheets. We are plotting the data we collected from our springs on Thursday. We want a properly entitled and labeled graph with a trendline and its mathematical expression. We will figure out what we can learn from your graph on Monday.
Assignment: You should bring your completed graph on Monday. There will surely be technical difficulties to overcome. We will address these Monday in class. We will also take a look at our solutions to the problems you received on Wednesday. The problems are from Chapter 6 in Giancoli: Problems 1, 10, 15, 17, 20, 24, 28, 43, 48, 58, 60. Your solutions will be due on Tuesday. |
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