Wednesday, 12 April 2017
While two of my classes took a unit test today, the third got sent outside to throw things in the air — for projectile motion. I asked them to show evidence as to whether or not the sportsball they chose was in equilibrium while flying through the air, considering horizontal and vertical equilibrium separately. Here they are filming their throws:
and here’s one group’s graph:
After 15 minutes of throwing, filming, and video-analyzing, we circled up and discussed. The evidence went something like this: See this position-time graph above? Because the vertical motion (in blue) shows changing velocity, it must have non-zero net force. And because the horizontal motion (in red) shows constant velocity, it must have zero net force.
Side note: I default to video analysis whenever possible, so my kids are good at it by now. We did this entire activity in about 20 minutes, including the discussion.