Countdown to Thanksgiving

Honors Physics sat through a quiz on rotational motion and gravity and then got a brief introduction to the concept of torque. The next chapter deals with rotational dynamics and we will move through the same topics that we covered when we looked at dynamics for linear motion. Tomorrow’s lab will focus on the nature of torque and its relationship to balance. Then, the lab will introduce a new perspective on equilibrium. We have been viewing equilibrium as a situation when an object experiences zero net force. However, a ball could experience zero net force (not moving across the ground), but still be rotating. There is another condition of equilibrium, where an object experiences zero net torque that also has to taken into account for rotating objects. Both conditions of equilibrium will be examined in the second part of tomorrow’s lab.

Physical Science B conducted a lab that investigated simple inclined planes and simple levers. Students calculated mechanical advantage and efficiency and tested how changing angle of incline and lever type affected these descriptors. Groups found that increasing the angle for a ramp decreases mechanical advantage – you are having to work against a larger component of the object’s weight as you raise the ramp. For levers, it was pretty quickly seen that even for the same class of lever, changing the positions of the resistance and effort forces had a big impact on mechanical advantage. Think about first class levers like crowbars and shovels in terms of what you learned in lab – why are these tools built the way they are? We’ll go over this lab tomorrow and begin our discussion of energy.

Physical Science E began their investigation of unit by reviewing the basic definition and unit for energy and differentiating kinetic and potential energy. We spent the bulk of the time discussing gravitational potential energy and practicing using the GPE formula. Remember that height is relative for this calculation and you must state or recognize the zero level for height measurement. Also, be mindful of sign…We breezed over elastic potential energy, although it is another stored energy of position. For EPE, the amount of stored energy is dependent of the amount of stretch or compression and how stiff/loose is the elastic material. We’ll go more into this type of energy in Grade 11-12 physics classes.

Physics F and G discussed the fabulous Randolph and used the discussion to review over basic descriptors and calculations relating to circular motion. We then focused in on the different types of forces that can be responsible for circular motion, which will lead us into tomorrow’s discussion of gravity. I’m looking at the assessment for this chapter when we return from Thanksgiving break – probably Tuesday – so keep that in mind for planning your time.

Homework

Honors Physics A: 8.1 Section Review and Practice 8A
Physical Science B: Complete lab write up
Physical Science E: Read p. 394-395 and complete the Practice on p. 395
Physics F and G: Conceptual Challenge p. 262, Practice 7H #1 and 4, Chapter Review items #32, 34.