Friction

Physics A and B enjoyed their Chapter 3 exam, but B Block got to take advantage of the scheduled long block and use the second half of the period to conduct a lab investigation on friction. Students investigated kinetic friction and how it was affected by the surface texture of the materials in question. Attention then turned to the coefficient of friction, which gives some quantitative measure as to how surface textures influence friction. We'll go over the lab tomorrow before heading (with A Block) into forces and Newton's laws of motion.

Introductory Physics reviewed for their Chapter 10 test, which is scheduled for Wednesday. We went over the weekend's homework before walking page through page through the chapter, highlighting information and skills necessary for Wednesday and pointing out things we covered in class that are NOT in the chapter. Folks were sent home with two packets of review material made up of questions from old MCAS exams. We'll go over them in class tomorrow and address any last-minute issues for Wednesdays assessment.

Honors Physics reviewed the concept of the normal force (F_N) and added in how to calculate the normal force when objects are on inclines and/or are being acted on by an applied force. Remember that the normal force generated by a surface will be equal and opposite to the magnitude of the force pressing down on it. If you are lifting up or pressing down on an object, that force will subtract or add to the object's weight (or component of the object's weight) and influence the size of the resulting normal force. We then linked normal force to friction. Static and kinetic friction were contrasted and will be the subject of Wednesday's lab. We looked at the factors that promoted frictional resistance and how the coefficient of friction and normal force were used to calculate the size of the frictional force an object experiences on or moving across a surface. We'll practice more with this tomorrow, along with how friction and the normal force factor into calculating the net force acting on a object and the resulting acceleration.