Day 78: Peer Instruction on Projectiles

proj1

Physics 11 – Today it was time again for more peer instruction. I had gone over the basics of projectiles with the class fairly briefly.  Somewhat different to how projectiles are covered in BC, I delayed introducing them until after we had done unbalanced forces.  At this point students can clearly identify the single force acting on the projectile and how it has constant acceleration downwards, and constant velocity horizontally.  Sequenced like this, projectiles do not have any new concepts in them.

This first question required two votes, but the students had almost 100% correct on the second vote.  The next question I knew would be more difficult:

proj2

The students had only one piece of the puzzle to figure out this question, and a few students picked up on it.  Most did not, even after two votes.  The concept that helps answer this question is that the time a projectile spends in the air depends on the vertical motion. Specifically, the more vertical distance traveled, the longer the time spent in the air.

I’m continuing to use Plickers for peer instruction, and it is working very well.  The software has improved over the past year and the voting appears to be more reliable.

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