Student "edition" found at {csi dot journalspace dot com}.

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

In the first mechanics lecture session of the fourth week of classes for the second term, from Constant Velocity in One Dimension that I talked about last time, I proceeded to Constant Acceleration in One Dimension.

First I defined acceleration, which is the change in velocity over time.

And just like in our discussion on velocity, before giving them the equations, I first gave them the concept in a table as time increases, with the velocity increasing (we had not encountered deceleration yet at that point) the exact value of the acceleration, and the displacement increasing as well.

They couldn’t intuit the pattern on the increase of the displacement, so I gave them a clue by showing the change in displacement from one second to the next.

This is actually equal to the average of the previous velocity and the current velocity, as if at the start of the second the object was moving at the old velocity, and at the end of the second was already moving at the new velocity, so its distance traveled was the average of the two.

I also told them that in the exam, they could use the table method if they wanted to. It will take more time, but if that was the way they comprehended the lesson, they could apply it.

From the table we derived the first two formulas, and from there we derived the next three, each with one quantity from the original five (acceleration, displacement, time, initial velocity and current velocity) missing.

But I assured them that they did not have to memorize that for the exam.

Then we proceeded to one example problem from the book. For this one I had to give them the tip that in analyzing the statements, they have to have a sense of which is the earlier velocity and which is the later velocity, if they are given, which at least one of them always is, or looked for.

Listing down all the given values, and, from the units alone, determining what variable it is supposed to be assigned, will give them an idea which of the five equations they would find it easiest to use.

Afterwards I gave them the admonition to always, as much as possible, use all of the given values in the item, and only use any of their previously computed values if there is no other choice for solving the problem. Otherwise, if their first computation were wrong, a domino effect would ripple to all the subsequent quantities asked for, and they could not get full points for those solutions.

Session 791 decelerates from a positive velocity to a grinding stop at this point. Class dismissed.