Day 15: Drag Calculation + Progress on Manual

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Day 15:  Drag Calculation + Progress on Manual

After watching (and for Jan Mark, participating in) the afternoon presentations, we worked on 2 projects.  We are nearly done editing the experimental procedure section of our lab manual write-up of the Free-Fall experiment.  The complete write-up should be ready by early next week so that we can get volunteers to try the experiment.

We were also able to use the ping pong ball data to calculate the drag coefficient, C, for a ping pong ball.

Ping Pong ball data
When air resistance is taken into account, the equation for acceleration of a falling body becomes:


where ρair is the density of air, A is the cross sectional area of the falling object and v is its instantaneous velocity. By plotting a vs the velocity squared, C can be derived from the slope. For typical falling objects, the range of C values is from 0.4 to 1. This graph is seen (will be inserted) below and the calculations give:


Giving a drag coefficient in the expected range.  This would be a very reasonable analysis section to add to the Acceleration Due to Gravity Experiment.

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