Brrrr.....

Mark your calendars – this was the first day this year I’ve had to scrape my windshield…

Honors Physics conducted an investigation into static and kinetic friction. Results were quite good – groups’ graphs for the motion of the objects looked as predicted and values for the coefficient of friction showed the predicted pattern as we changed the mass of the system. Tomorrow, we will discuss the lab, go over the homework problems and tidy up any loose ends before Friday’s exam.

Physical Science B reviewed their Newton’s 2nd Law of Motion Lab and built on yesterday’s work with orbital motion with a discussion and demonstration of projectile motion. Take home message – projectile motion is 2-dimensional motion and the x-(horizontal) and y-(vertical) components of the motion are independent of each other. The horizontal motion is at constant velocity (if we discount air resistance) due to the lack on an unbalanced force to accelerate the object. Motion in the vertical direction is accelerated by gravity, so the velocity in the y-direction increases with time. We also started looking at Newton’s 3rd Law of Motion and will continue on with that discussion tomorrow.

Physical Science E completed their examination of projectile motion with a demonstration of the independence of the horizontal and vertical motion vectors and launched into a discussion of Newton’s 3rd Law of Motion. Probably the most misunderstood of his laws of motion, Newton’s 3rd refers only to the magnitude and direction of the forces generated in an interaction between two objects, not to the responses of those objects to the forces. You have to back to Newton’s 2nd Law of Motion to determine the resulting acceleration of the objects. Our work with Newton 3 will lead us into another very important concept in physics – momentum and its conservation.

Physics F discussed the nature of static and kinetic friction and the use of the coefficient of friction in determine friction’s magnitude. Note that I changed the homework assignment by omitting #3 of the 4.4 section review. Physics G engaged in an examination of air resistance and terminal velocity. Tomorrow’s lab will concentrate on the impact of air resistance on the motion of objects – contrasting a low-inertia and high-inertia object as they fall. Both groups should be looking towards next Tuesday for their Chapter 4 exam.

Homework

Honors Physics: Complete lab write up (for Monday) and homework problems
Physical Science B an E: None
Physics F: Practice 4D #2 and 4.4 Section Review #2, 4-6
Physics G: Read lab sheet. Complete p. 153 #32-36 for Friday