Exam Prep Tuesday

Honors Physics reviewed their lab lever and pulley lab activities and then moved into a general review for tomorrow’s exam. I will collect the homework we went over today in class before the test tomorrow, so don’t forget the papers at home! The formula sheet that you have seen for every test will be the same one that you will use tomorrow, so just be sure you are able to identify all of the relevant variables in the equations. Starting on Thursday, we begin to look at how forces interact with fluids and hit topics such as buoyancy, fluid pressure, flow rate and gas laws.

Physical Science B and E reviewed for their work and energy exams. We will use the MCAS formula sheet tomorrow, along with a few additional equations that we used in lecture and lab this unit. Take time tonight to rework every type of problem that we’ve encountered and make sure that you can adequately respond to each of the objectives that are at the beginning of each section in the book. Starting on Thursday, we will move away somewhat from motion and begin to focus on one of the forms of energy that we mentioned in this chapter – Heat.

Physics F shared their lists of members of the inclined plane family and then began an examination of efficiency. Due to the fact that some work/energy is always converted into nonmechanical or non-useful forms, a machine can never give out all of the energy/work that you put into it. It always has an efficiency less than 100%. This also means that, machines (including you!) must always be fed with fresh energy to continue to function. Make sure that you are clear about the difference between mechanical advantage and efficiency, as you will examine both of those in your lab tomorrow with simple machines.

Physics G conducted a lab investigation that allowed students to see how levers and pulleys manipulate force/distance to make your work easier. The mechanical advantage and efficiency of the machines and their variations (1st and 3rd class levers; simple fixed, movable and multiple pulleys) was calculated, with data falling about where we would expect it. First-class levers can give MA>1, but third-class levers don’t have that ability. Pulley systems and movable pulleys can give MA>1, due to the increased number of supporting ropes (increased input distance), but simple fixed pulleys give MA=1. Their benefit is in the change of direction of force. Tomorrow, we will review the lab and the basics of simple machines before moving into the concept of efficiency.

Homework

Honors Physics A: Study for Chapter 8 exam
Physical Science B and E: Study for Chapter 12 exam
Physics F: Complete simple machines worksheet
Physics G: Complete lab write up