Download Lab3PreLab

Pre-Lab for Lab 3
In Lab 3, we are going to be applying different forces to a system of constant mass, and measuring
the acceleration the system undergoes. A glider will be pulled by
a weight hanging over the end of an air track; the weight provides
a constant force, accelerating both weight and glider. Our set-up
will make the total moving system be the glider plus the weight.
By moving ballast masses from the glider (m1) to the weight (m2)
and vice-versa, we can change the amount of force applied to the
moving system without changing the total mass being affected by
the driving force.
The alternative would be to keep m1 constant and add weights to m2. This would vary the total
mass of the system while applying more force.
Calculations
Assume that m1  m2 sum to a total mass of 0.300 kg. The mass m2 varies over the range
0.010 kg ≤ m 2 ≤ 0.070 kg . Both masses will begin at rest, and then be subject to a force
equal to m2 g , where g is the acceleration of gravity, 9.80 m s-2. That force will be applied to the
0.300 kg total mass of the moving system.
For four different values (10, 30, 50, and 70 grams) for m2 compute the acceleration of the whole
moving system (remaining with total mass fixed at 300 grams), its velocity at a point 1 meter past
its starting position, and the time to reach that point from its initial, at-rest position. Present these in
a four-column table. Plot the acceleration versus m2 in one color.
Next, make the same kind of calculation, but assume that the m1 is fixed at 0.290 kg. Then assign
to have masses as above (10, 30, 50, and 70 grams) and compute the aceeleration of the whole
moving system (which now has varying mass, so make sure to include that in your calculation!). In
a different color, add the acceleration versus m2 points and curve to your plot above, and comment
on the difference you see. Which case should produce a straight line in your plot?
PHYS 121, Summer 2010
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