A Day o' Math

Honors Physics rode through weight and the normal force in fine fashion today and then began to wrestle with friction. We discussed both static and kinetic friction and will take time tomorrow to more fully contrast the two and examine methods for calculating frictional forces. The ability to resolve an object’s weight will be very helpful for problems that involve motion on an incline. Adding weight, normal force and friction to the pot will make analyzing motion of objects a bit more complex. Take care drawing your free-body diagrams to isolate all forces in play and consider how those forces will be calculated. Acceleration is only produced by the net external force, so if you leave a force out of the picture, you will incorrectly describe the object’s motion.

Physical Science B rioted for awhile when they realized that math is going to plague them throughout the year and that they had best get used to working with equations and their calculators. Today, we reviewed the universal gravitation formula and the problems that we assigned last night. From what I can tell, calculator use is a major issue, as is working with a multivariable equation. You will get lots of practice with both this year, so a rocky start doesn’t mean that you are doomed completely. Take time tonight to rework the homework problems and ask yourself if your difficulties lie in setting up the problem, your solution method or problems with your calculator. If you need extra help or additional problems to work, feel free to ask. Tomorrow, we continue on with gravity and the acceleration that it produces on objects.

Physical Science E discussed yesterday’s lab, which nicely demonstrated the relationship between force, mass (inertia) and acceleration predicted by Newton’s 2nd Law of Motion. We went over our homework problems from Monday and began a discussion about gravity. They also received the dreaded universal gravitation problems packet. Check the previous post for the link to the solutions key for that problem set. We will go over them tomorrow, but do your very best to work through each problem as far as you can. As for all math problems, try and figure out where your main difficulty lies and ask for extra help on that piece.

Physics F discussed their lab investigation and discussed the nature of forces and the use of force and free-body diagrams to analyze forces acting on an object. Tomorrow, we will learn how to calculate the net force acting on an object and the acceleration produced by that force. Physics G had that discussion today, along with an examination of Newton’s 3rd Law of Motion. From the Vernier demo, it was pretty clear that forces generated in an interaction are equal in magnitude but opposite in direction. That pattern holds whether the interaction is between two Sumo wrestlers, a mosquito and a car or a baseball and baseball bat. Remember that the idea of equal and opposite, though, applies to the forces involved, not the responses of the objects.

Homework

Honors Physics: None
Physical Science B: Rework gravity problems, as necessary
Physical Science E: Gravity problems worksheet
Physics F: 4.2 Section Review and #1-5 on page 151
Physics G: p. 152 #13-18, #20