Wet Wednesday

Honors Physics completed the work and energy unit with a discussion of energy conservation and power. As you work problems with energy conservation, remember to take into account all forms of mechanical energy present at the beginning and end of the situation in question. Also, if elastic potential energy is in the picture, you can’t cancel out mass in the way you can when only kinetic energy and gravitational potential energy are involved. It also pays to take time to look at a problem wearing your force/kinematics hat, as well as your work/energy hat. Consider how you would describe or explain a situation using forces and kinematics and see how that description/explanation can also be matched by using work and energy concepts. When you get to the power problems, you need to reflect on the variety of ways that we can express work – force x distance, change in energy, etc. – to see how best to approach the power issue. Also, don’t forget the force x velocity derivation. That can come in handy in certain situations. Tomorrow, exam review. Friday, exam.

Physical Science B began their study of forces in fluids today with a discussion of pressure. Make sure that you are clear about the difference between force and pressure and how manipulating force and area create different pressure situations. We then turned towards the tendency of fluids to move from areas of high pressure to areas of low pressure and the implication this motion has for matter that lies in a fluid’s path. We discussed breathing, drinking from a straw, vacuum-cleaner function and hazards of traveling in space without a pressure suit. Tomorrow, we take up the possibility that fluids are blocked from motion – what happens if you apply pressure to one part of a fluid, but don’t allow the fluid to move? Think hydraulics…

Physical Science E had a wet and wild lab experience. The pressure change in a water column due to depth was investigated and, despite a few floods, data for all groups was great. A clear linear relationship between pressure and depth was witnessed: with greater depth comes greater pressure. The same trend exists in all fluids, including the atmosphere. The pressure is highest at sea level and decreases with altitude. The types of problems you worked at the end of the lab are typical of those that scientists and engineers use when they are designing equipment or experiments to work at a certain depth in an ocean or lake or at a height in the atmosphere. Tomorrow, we’ll review the lab and begin discussing the source of pressure in fluids.

Physics F and G discussed power and cleared up some misconceptions about the concept of power. We took time to complete going over all the previous homework problems and that will lead us into our exam review tomorrow. Look over the chapter tonight and come with any and all questions for exam preparation.

Homework

Honors Physics A: Complete Practice 5F #1,2 and p. 195 #33-36
Physical Science B: None
Physical Science E: Complete lab write up
Physics F: Complete 5.4 Section Review
Physics G: Study for exam