Finally Friday!

Honors Physics discussed the simple machines today, along with mechanical advantage and efficiency. At some previous point in time, most folks have been introduced to the simple machines, so today’s work was a good refresher and an opportunity to tie simple machines to the concept of torque. On Monday, students will engage in a lab that allows them to study the classes of levers and simple/multiple pulley systems for ideal/actual mechanical advantage and efficiency. Tuesday, review; Wednesday exam. Thursday – starting fluid dynamics.

Physical Science B conducted their conservation of energy lab investigation and the results were pretty good. The re-distribution of energy between gravitational potential and kinetic was evident and there was fairly good indication of conservation of mechanical energy. Of course, with a real system we don’t expect conservation of mechanical energy – the conversion of energy to nonmechanical forms robs a lot of the useful energy from the system, and your results definitely bore that out. Have these labs written up to go over on Monday, when we will also start reviewing for the exam, which will be on Wednesday.

Physical Science E had additional time to work on their conservation of energy problems and get extra help from me. As there were only six people present due to the band/chorus concert, moving ahead with new material wasn’t the best option. Monday, we will go over the problem worksheet and discuss the idea of efficiency – how well does a machine conserve mechanical or usable energy.

Physics F and G began their study of simple machines by discussing the basic function of machines and concentrating on the lever family. All machines make work easier, but at a cost. A machine will either multiply your effort force (but at the cost of distance) or multiply your effort distance (but at the cost of force). No machine can multiply both components of the work/torque formula simultaneously. Levers are very good at multiplying effort force, generating a mechanical advantage greater than one, but some, like simple fixed pulleys, only change the direction of the force. Others, like third-class levers, actually diminish effort force, but give you greater output distance in return. Monday, we will examine the inclined plane family and see how its members approach making work easier. Your lab for this unit will investigate the three classes of levers and various configurations of pulleys for ideal mechanical advantage, actual mechanical advantage and efficiency.

Homework

Honors Physics A: Chapter 8 Review Worksheet and Chapter Review #20, 53, 67
Physical Science B: Complete lab write up
Physical Science E: Complete conservation of mechanical energy problems
Physics F and G: Make a list of 30 members of the lever family. Remember not to repeat examples of the same lever - bike wheel and car wheel count as the same, not separate levers.