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[Phys-L] Re: coefficient of friction or drag



Of course, the purpose of a parachute is to cause the descent to
reach an acceptable terminal velocity. Otherwise, the velocity is
continually changing due to the gravitational acceleration.
What velocity are you considering? Are you planning to compare the
expected velocity at some point due to free fall from the maximum
height with the actual velocity due to drag? Are you using the time
of descent as the comparison? Karl

I am planning to conduct a model rocket project with a high school physics
class and I wanted them to collect data on their rockets.
One of the variables that I wanted them to determine is the coefficient of
friction or drag on the parachute as the rocket came back down.
I wanted to get an opinion on the best way to accomplish this.
My first thought was to have them find the velocity of the rocket on its
descent and calculate the velocity of the rocket where there is no friction.
Then use the frictionless rocket as the accepted value and the velocity they
found for their descent as the experimental value.
(Accepted value minus experimental value)/ accepted value. The difference
in the velocities is due to friction or drag.

What might be a better way?
They will know the beginning mass, ending mass, altitude, and time of flight
both up and down.


--
Dr. Karl I. Trappe, outreach consultant Home (512) 264-1616
Research Scientist Associate V, Desk (512)
471-4152/471-1823 Senior Lecturer in Physics
Physics Department, Mail Stop C-1600
The University of Texas at Austin
Austin, Texas 78712-1081