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

Going back to my mechanics class last Monday, I taught them about two-dimensional motion, particularly projectile motion.

Looking at the schedules of the three computer labs, the one I found to be free at the same time as our c lass turned out to be the one where they were having their class before mine, I just asked permission from their teacher (Alain) if I could give an announcement.

I told them that if I returned before their class ended that means my request for our class to be moved to the lab had been approved. Otherwise, we would meet back in the classroom.

Luckily, my change of room request (for that session alone) wasn’t denied.

Now, on to my lecture: since a handful of them were also my students in Trigonometric Application, they were already familiar with getting the x and y components of a vector given the magnitude and the direction (angle).

From there I told them that horizontal motion is still governed by the same rules as before of constant velocity in one dimension, while vertical motion is still governed by the rules of free fall or constant acceleration due to gravity.

These I allowed them to input into spreadsheet software, using the supposedly familiar equations for getting the position (along x using constant velocity and along y using constant acceleration) placed in two columns with the initial velocities and with changing time.

After they have determined the that second column (the first column contained values of time) followed the rules on constant velocity and the distances differed by a fixed amount, and that the third column followed the rules on constant acceleration with the distances differing by an increasing margin, that was when I allowed them to plot the chart of the two columns in a two dimensional graph.

I also taught them the reverse, how to get the original vector of velocity and angle given the x and y components of the velocity.

Then I gave them the equation for the range of a projectile, which is only applicable for when the projectile returns to its original height. For this I had to give them the three common scenarios of projectile motion, depending on the relative stopping point to the starting point: same height, higher or lower.

I told them that the range could not be computed for the second scenario and that for the third scenario, unlike the first scenario the range does not equal the total horizontal displacement.

Afterwards I showed them how the same equations for converting vectors along the axes could be applied for forces and for acceleration, by showing that Newton’s Second Law could now be rewritten for both x and y subscripts.

At this point there were already some students asking for examples, but since I knew the computer screens in front of them was very distracting to their attention I told them that we would have sample problems next meeting based on the concepts we discussed.
I’ll end here for today. I’ll continue tomorrow. Class dismissed.