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Phy 231
Your 'cq_1_20.1' 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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The situation here is similar to that depicted above, though the
distances of the rubber bands from the center are different. The
die on which the strap rotates is not visible, but is attached to
the tabletop; the blue push pin constrains the system to rotate
about a vertical axis through the center of the die.
The problem:
The metal strap used in the Angular Velocity of a Strap
experiment is constrained by a vertical push pin to rotate about
a hole in a die. The die is glued in place to a massive
tabletop. A rubber band is attached to a point 15 cm from the
axis and stretched so that it exerts a force of 3 Newtons,
directed perpendicular to the rod. If this force is unopposed it
will accelerate the system rapidly. You want to attach a second
rubber band 5 cm from the axis to prevent the system from
rotating.
How much force will that rubber band have to exert?
answer/question/discussion: ->->->->->->->->->->->-> :
t = F * r
t = 3 * 15
t = 45 N * cm
so, t = 45
and t = F * r
45 = F * 5
F = 9 N
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Once both of these forces are in place and the system is
stationary, what (if anything) will happen if the glue holding
the die to the tabletop comes loose?
answer/question/discussion: ->->->->->->->->->->->-> :
The system should not rotate because it is in equilibrium.
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@& The system encounters forces of 9 N and 3 N, in opposite directions. This does not imply equilibrium.
If the glue holds, then the axis of rotation is held in place. If the glue breaks loose, the system will accelerate away from this position.
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