Lesson #2—Energy Types—for each video, take notes, copy the example problems, and write-down any questions you have.
· Watch #3—Intro to Kinetic Energy with Example.
s Mr. P says that “v” in the KE equation is the velocity of the object. It is actually the magnitude of the velocity at the instant being analyzed, or we could call it the object’s instantaneous speed.
s Pause the video at 1:31, after Mr. P asks Bobby if KE can ever be negative. What do you think? Give your reasoning.
s Example Problem Statement: Let’s say I am riding my bike at 25 miles per hour. How fast would I have to drive my Prius so that I would have the same amount of kinetic energy as I do when I ride my bike? The mass of me on my bike is 86 kg and the mass of me in the Prius is 1400 kg.
s You’ll notice that when a variable, like mass, cancels-out during the solving of a problem, they play a little song…just try to ignore it if this bothers you!
· Watch #4—Intro to Gravitational Potential Energy with Example
s What is the “horizontal zero line”? Who decides where to put this line?
s Briefly describe how an object could have negative gravitational potential energy.
· Watch #5—Intro to Elastic Potential Energy with Example. NOTE: Mr. P uses “PEe” to represent elastic potential energy. I will use “PEs”, where the “s” stands for “spring”.
s Pause the video at 2:50 when Mr. P asks about the spring constant for a Slinky. What do you think?
s Example Problem Statement: Let’s determine the elastic potential energy stored in the rubber band (with a spring constant of 241 N/m) when it is elongated 12 cm or 0.12 m.
s Pause the video at 6:37 when Mr. P asks about negative PEs. What do you think?
Tomorrow in class, you will get some practice working with the three equations you learned last night.