Day 13: Fan Cart Lab

FancartGraph

AP Physics C: Here’s the velocity-time graph for a fan cart that received a brief push from my hand, then slows down as it rolls away from me, picks up speed as it rolls back to me, then is stopped by my hand. Notice that the acceleration while the cart was rolling away from me is NOT the same as the acceleration when it rolled back. This is because friction is not negligible and changes direction. A free body diagram for the away and return trips will show you how.

It was then put as a challenge to students to use the momentum principle and the data from the Logger Pro file to find the magnitudes of all the forces acting on the cart:

  • the gravitational force from the earth
  • the normal force from the track
  • the thrust from the air
  • the frictional force from the track

Later, we’ll create a model in VPython and check our model data against our laboratory data.

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About Frank Noschese

HS Physics Teacher constantly questioning my teaching.

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