Forces

Introductory Physics took time to review yesterday's lab that focused on the topic of friction. We'll add a number of details to our discussion about friction during tomorrow's class, but the information we went over today should be enough to help you interpret your data and write up your lab. We postponed the due date for that from tomorrow to Monday, so you should have plenty of time to craft a good conclusion section, including any research time you might choose to use to enhance that section of your lab write up.

Honors Physics reviewed their work on Newton's 1^st and 2^nd laws of motion before tackling the last sibling in that series of triplets - Newton's 3^rd law of motion. This one sometimes gives people a little difficulty, so be clear that you understand that forces occur in pairs. Each member of the pair is equal in magnitude, but opposite in direction to the other. This does not mean, in any way, that the accelerations of the interacting objects will be equal and opposite. The accelerations will be based on the object's inertia, measured by their masses. So, if a mosquito hits a car's windshield, the mosquito and the windshield both experience the same magnitude of force. However, the mosquito will have a much larger acceleration due to the smaller inertia. Newton's 3^rd works with contact forces as well as with field forces such as gravity. In our discussion of weight (F_g), we used the pull of gravity on objects to show how both objects are influenced by the shared size of a pull, but how their resulting behaviors differ. Tomorrow, we'll start to look at the remaining of what your book calls "Everyday Forces," - the normal force (F_N) and friction (F_k,s).

Physics A and B reviewed their work with projectiles launched at an angle and took more practice with that topic during the class period. We'll have a general review for this chapter in class tomorrow to prepare for Monday's exam, so come with questions!