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Phy 231
Your 'collaborative labs' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
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Idea 1:
We will first set up a mechanism that will allow a calibrated rubber band to be stretched and released in a way that will apply the band's force to a rotating strap.
I think this could be accomplished by using one of the pieces of foam insulation to affix the center of the strap with one push pin so that the strap lines up with the bottom of the foam rectangle. Then a pin would be placed along the right side of the foam rectangle, a few inches above the strap (so the strap and the upper pin form a right triangle with the hypotenuse to the left). That upper pin needs to be outside the radius of the circle formed by the rotating strap.
Holding the strap in place with one hand, we will stretch a band around the upper pin and the strap, then let go of the strap so it begins to rotate. We will then time the rotations, or simply count them, and compare the rotational behavior to the amount of force generated by releasing the band. (So, we'll have to move the upper pin a few times to compare different stretch levels.)
Idea 2:
We will make a pendulum out of a domino, then release it from varying heights, allowing it to strike a marble positioned on the edge of the grooved track (itself positioned on a level surface so the marble can balance with a bit sticking out beyond the rails of the track) just before it reaches equilibrium.
We will time the marble's trip from one end of the grooved track to the other. This will allow us to compare the initial PE of the pendulum to the resulting KE (determined through calculating vAve of the marble). I'm not certain that there isn't more to the initial PE than just the gravitational PE, or if gravitational PE converts differently when applied through pendulum motion rather than free fall, but generally I believe that the momentum of the domino as it strikes the marble will vary based on the height it started from, which will allow us to see conservation of momentum through the behavior of the marble.
Idea 3:
Elevating one end of the plywood to make a wide ramp, we will take three dominoes and race them down the ramp by holding them at the top with a ruler or some other flat object, then pulling that object away to allow them to slide down.
Two of the dominoes will be altered to change the frictional force. We can do this by taping two different types of paper on the bottom of them, for instance: wax paper and a paper towel, or aluminum foil and construction paper. Then we can time the trip down the ramp and compare the results.
While we don't have a way to calculate the coefficient of friction on the unaltered domino, we can compare the relative friction on different types of surfaces with only negligible differences in mass. This may be more useful if we release the dominoes from several different heights.
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Very good ideas.
We'll follow up soon.
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