Day 60: Applying Fnet Model to Problems


Physics 11 – Today the students were given a handout to summarize all the types of forces they have learned up to now.  I then prompted the students to solve some word problems, and went over the solutions after everyone had tried them.  By “everyone” and “tried”, I really mean that.  I’m well aware the studenting that happens in high school.  Many students sit there, fake it, or take bathroom breaks, so that they can simply copy down the correct answer once I go over it.  The solution?

  • Walking around, the classroom, help the ones that are truly stuck
  • Mostly leave alone the ones that are getting (but still check in)
  • Finally reveal an answer once everyone has seriously tried the question

I even heard students say they were going to wait until I go over it.  I’m not sure what they would learn from that.  Surely me going over it is no different from reading a textbook, or close to it.

Day 58: Unbalanced Forces Results


Physics 11 – Today the students wrote up their results from their lab for Newton’s 2nd Law. Many groups were getting close to developing a model for Newton’s 2nd Law: Fnet = ma.  Since the input for the lab was a force though, the students graphed a = Fnet/m

Once the slope was written as a fraction, the students were able to recognize that it was the inverse of the mass.

I have two classes of physics 11.  During the first class, I walked along a lot and spoke with students as they worked.  As a result, by the time we got to share the whiteboards, almost everyone had the same board. For example, I challenged groups to find better symbols to use, rather than x and y.  The second class I helped a lot less and the following discussion was better.

After our discussion, the students applied their new model to the situation of someone standing on a scale inside an elevator.  This allowed for some thoughtful thinking on adding forces together from well drawn force diagrams.