Maybe I shouldn't have started this blog now, not with everything that's been going on.

Twelfth week of classes, third trimester, Advanced Mathematics course, second meeting: Giving them, as usual, the chance to redeem themselves from their quiz, I gave them the same questions, divided the class into two groups, and let them answer until the end of the period. It will be kudos to them if they remembered how they solved the problems, but at least they had the advantage of consulting with their classmates’ notes.

For the second meeting of my mechanics lecture students for week twelve of classes, we discussed frictional forces in one and two dimensions.

Again I emphasized to them that just like with weight and tension, the definition of the forces (friction and normal) gave an idea as to their direction in the illustration of the problem, which is always the first step in their solution excluding listing down the given.

In fact, a clearer name for the classification of our examples would be horizontal/vertical forces and inclined/angled, since even the supposedly one dimensional motion examples still had to deal with the vertical forces, even if it was just the normal force and the weight.

The next step in their solution is then coming up with the two summations of forces along the two set axes, whether x and y or parallel and perpendicular to the motion/surface.

Then they have to determine what equation to use to solve for the unknown. If they do not have all the quantities given to substitute and compute in the formula, they either have to look for another formula or try to substitute other formulas to get the other subsidiary variables in their initial formula.

I also had to emphasize to them the difference between solving for static friction and kinetic friction.

For the first, the product of the mass and the acceleration is a number that is almost zero but still greater than zero.

For the second, the acceleration is zero if the object is moving with constant velocity. Otherwise, acceleration is a value that has to be solved.

I also showed them that the above is the reason why we could not use horizontal and vertical components when dealing with motion on an inclined plane – neither summations on both axes would not equate to zero or near zero and this simplify their solution, although I welcomed them to try to solve it, especially with up to six trigonometric functions (instead of two) that had to be plugged in.

I heard some students complaining that they got the first part of the lecture (about the horizontal or one dimensional friction) but that they got confused with the second part.

That’s why we have a make up session scheduled at the start of the thirteenth week to give them more time to practice and learn before the exam during their supposed first meeting on the thirteenth week.

I’ll discuss the Electromagnetic Theory session next time. Class dismissed for this week.