A Baseball Pitcher Does Positive Work on the Ball by Transferring Energy Into It

A baseball pitcher does positive work on the ball by transferring energy into it. Schemm*Physics Weekly Homework #12 Work, Power, Energy (PE and KE) Due Tuesday February 2nd, 2010 For additional online content visit www.schemmscience.com

Read/Notes p. 103-119 in Hewitt's Conceptual Physics

4 PhyzSpringboard Worksheets [ Work | Potential Energy | Kinetic Energy | Power] In class we will discuss both Work, Potential Energy, and Kinetic Energy, using these three worksheets as sort of guided notes. Be sure to get the sheets that have the Introduction to Work Springboard, Potential Energy Springboard, and the Kinetic Energy Springboard. I will use the overhead to walk through these sheets with you…so there is really no reason you can’t get these in with the Homework.

WebAssign WebAssign for HW #12. We’ll get a start in the computer lab this week, but be sure to bring a pen and paper to work out the algebra for these questions! Solve Show all your 'work'. Remember to include the correct units. 1. How much work is done by a crane that lowers 1000 Newtons of material a distance of 150 meters? 2. How much work is done when a 500 N mass is raised a vertical distance of 10 meters? 3. A 5 N rock is lifted 2 meters in 5 seconds a. How much work is done? b. What power is used? 4. For the following four examples, determine if there is work done on the system. Explain your rationale for each.

StairMaster In class you will be given a period to investigate the work and power you generate when ascending the stairs. As a class we will compare the horsepower output for each of us. This work and power lab will be due with this homework. Be sure to show sample calculations and have compounded your calculations to express your results in Horsepower (Hp).

PhyzJob- Conservation of Energy at the Amusement Park (on the back) This worksheet, while only 6 questions, hits on each one of the topics we are covering for the week. There is a piece on Work, Power, KE, and PE…all with 6 simple questions. I would advise trying this worksheet after you have done the majority of the other work for the week…or like everything else in this homework…just save it for the last minute… Extra Credit In the world there seems to be a general misunderstanding as to what work really is. Physicists know that work is a product of force and distance, but few others realize this. You’re asked to start a propaganda campaign making a sign stating that people who are working really aren’t. I’ll provide some examples in class. Be creative and/or hilarious.

Brake It As a class we will venture outside to test the new brakes in Schemm’s car. (weather permitting) Your driver’s ed class says for each 10 mph increase in speed you should allow for an additional car length between you and the auto in front of you. Applying what you have learned about energy; is this a valid rule-of-thumb? Be sure to show any supporting information with your explanation. Calculations and graphs will be helpful in your argument.