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Phy 241
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.
** CQ_1_20.1_labelMessages **
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: ->->->->->->->->->->->-> :
= Force times distance
= 3 N * .15 m
= 0.45 N-m
0.45 N-m / 0.05m = 9N
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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: ->->->->->->->->->->->-> :
according to the picutre the forces of the rubberbands will cause the rod to be pulled in the direction of the forces, and since the 5 cm force is larger,
the rod would rotate slightly in a counterclockwise motion
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The two forces would act in the same direction. Without the force of the glue, the center of mass of the domino and strap will accelerate in this direction. There will also be a rotational motion due to a net torque on the system. The net torque will change as the rubber bands relax, as will the net force. The motion of the system will be fairly complex.
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