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Re: [Phys-l] gravitational force



These are not 'labs' in the sense of taking data, and the first may not be appropriate at a HS level, depending on student's math and experience, but....

1) Using a spreadsheet, explore an object falling from a great height (I do a bowling ball--since I use one as a constant prop falling from 100 km up).
If you ignore air resistance, then you can construct a simple spreadsheet where you can use 1 second increments and calculate the acceleration at the starting height, then the velocity after 1 second using v(f) = v(0) + a(delta-t). You can find the new height with H(f)=H(0) + v(delta-t). Now use the new height to recalculate 'a'. Repeat the process (if properly written just copy your last row down to fill a couple hundred rows and find the time when the ball is back at the surface. You can plot height versus time, and velocity versus time--even velocity versus height.

[When I use this I have students redo this with an air-resistance term, first assuming a constant damping factor, and then again calculating 'b' assuming a linearly decreasing air density with height. You can proceed to model the air density more precisely if wanted. None of this, though would be appropriate at the HS level, but the simple no air-resistance exercise might be.]

2) Break up into a number of groups. Assume the Olympic games were to be held on the moon, in a domed stadium filled with air at normal earth pressure. Assign each group an event. Have them reason out, based on the moon's gravitational force, whether the performance in their event would be better, worse, or the same as on earth. If different, have them try to do a simple calculation. [While this one might not seem to be getting at your stated topics, you will find a number of students will initially think there is NO gravity on the moon.]

3) Again, in groups, have students design a communications satellite system to provide global coverage.

Rick

***************************
Richard W. Tarara
Professor of Physics
Saint Mary's College
Notre Dame, IN
rtarara@saintmarys.edu
******************************
Free Physics Software
PC & Mac
www.saintmarys.edu/~rtarara/software.html
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----- Original Message ----- From: "Mike VanAntwerp" <mvanantw@hpsk12.net>
To: <phys-l@carnot.physics.buffalo.edu>
Sent: Tuesday, October 31, 2006 12:13 PM
Subject: Re: [Phys-l] gravitational force


Sure- thanks for the sarcasm. I'm looking for ways to get students to
work with Kepler's Laws and F= G (m1m2/d^2) in a lab setting. This is
for a high school class.

Mike Van Antwerp
Biology W202