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Re: Newton's Second Law Lab



John, no need for an apology. Your idea is the only really new one that I
have seen posted so far. I like it very much and, if I may, I will steal
it from you!

Alex





John Gastineau <john@GASTINEAU.ORG>@lists.nau.edu: Forum for Physics
Educators" <PHYS-L on 07/04/2000 09:25:48 AM

Please respond to "phys-l@lists.nau.edu: Forum for Physics Educators"
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Sent by: "phys-l@lists.nau.edu: Forum for Physics Educators" <PHYS-L


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Subject: Re: Newton's Second Law Lab


Use a force sensor and an accelerometer on a cart. Zero both. Start
collecting
data, and grab the hook of the force sensor. Wiggle the cart back and forth
so
that the only horizontal force applied to the cart is through the force
sensor.

The graph of the acceleration will be the same random shape as the force
graph, indicating that there is a deep connection between force and
acceleration. Then make a plot of force vs. acceleration. Regardless of how
the cart was moved, the force vs. acceleration graph is a straight line
passing through the origin. The slope is the (inertial) mass of the cart
and
sensors. Of course, this then begs the user to add mass to the cart and try
it
again.

The neat thing about doing the lab this way is that you're making
independent
measurements of force and acceleration, AND that you're showing the second
law
for general, time-varying forces, not just constant forces.

My apologies if this idea has already been posted; I'm at a conference all
week and only have occasional Internet access.

__________________________________

John E. Gastineau john@gastineau.org
953 National Road, #163 (304) 243-9636 voice
Wheeling WV 26003-6440 (304) 243-9637 fax
USA http://gastineau.org
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