Return from Turkey Day

Honors Physics A started their discussion of rotational dynamics with a look at torque and moment of inertia. Torque – the ability of a force to produce rotation around a specific axis. We have insert that “specific axis” in that phrase since different axes of rotation are easier to spin around than others. That’s where moment of inertia comes into play. Moment of inertia looks at different configurations of mass and describes the resistance of that shape to rotation. Take a single object and try to rotate it in different ways. Some ways are easier than others – that is due to the distribution of mass around the rotational axis. The more of the object’s mass that is close to the rotational axis, the lower the moment of inertia and the easier is the rotation. Tomorrow, we’ll extend these ideas to conquer rotational equilibrium – how do you calculate the forces and torques on objects that exist in equilibrium? For tonight's homework, if I don't have time to update the class website, you can USE THIS LINK for the solutions for Chapter 8 problems.

Physical Science B went over their gravitational potential energy and kinetic energy worksheet. We then discussed the other forms of energy such as chemical, nuclear, heat and electromagnetic. We will spend time with heat and electromagnetic energy later in the year and may get a chance to hit nuclear, time permitting. You will discuss chemical energy in detail in biology and chemistry. Tomorrow, we begin an examination of conservation of energy, concentrating just on kinetic and gravitational potential as our examples. Exam looks like it will fall on Monday, so you should have plenty of time to prepare.

Physical Science E also discussed forms of energy and took time to analyze the nutritional label of a pack of cheese to determine how energy is apportioned between the main biological molecules – fats, carbohydrates and proteins. Most people don’t realize that the calorie is a unit of stored energy – how much work could you do if you ate this food – and that different molecules store different amounts of energy in their chemical bonds. Tomorrow’s lab will center around the conservation of energy, specifically mechanical energy, but know that all energy is conserved regardless of form or type. Some of it does not remain in a form or type usable for work, though, and that’s what we mean when we say that energy is “lost” in a system.

Physics F watched a video on anti-gravity machines and worked with examples of rotational motion. The rheoscopic balls were especially nice for looking at how individual regions of a rigidly rotating object compare for angular and tangential speed. By tomorrow, you should have your film and activity questions completed, as well as the review worksheet. Exam on rotational motion and gravity tomorrow and then onto torque and machines! Physics G reviewed for the exam and worked on their preparation worksheet. Have your worksheet ready for tomorrow, as they will be collected before the exam. For both sections – the formula sheet will have all of the angular motion formulas available, but make sure that you know what all the variables stand for!

Homework

Honors Physics A: Read section 8.2 in the book and complete Practice 8B
Physical Science B: Complete the 12.3 Section Review
Physical Science E: Read lab sheet for tomorrow’s activity. Complete Graphing Activity p. 409 and 12.3 Section Review for Wednesday
Physics F: Complete lab questions and review worksheet. Study for exam.
Physics G: Complete review worksheet. Study for exam.