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ThomasMagnus
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A window washer pulls himself upward using the bucket pulley apparatus shown. How hard must he pull downward to raise himself at a constant speed? The mass of the person and the bucket is 65kg.
My attempt:
When doing pulley problems, I like to set 'moving to the right' as positive. In this case, there are two forces acting toward the right side and one to the left.
The force that the washer pulls with will be equal to the force that the rope applies on the bucket
The forces acting on the bucket: FT-mg=0 (constant acceleration therefore a=0)
Forces acting on the right side: FT=0
Add the two equation together:
2FT=mg
mg=637N
FT=319N
My question is: How can he be moving at constant velocity if there is an unbalanced force acting on the right side? Is it because there is no net force acting on him? (i.e FT-mg=0) If he is moving at constant velocity, can there be a net force on one side of the pulley, but not on another. Or if he is moving at constant velocity, does there have to be a net force of zero on the entire system?
If the sum of the forces acting on the washer and bucket is zero, then is he at rest or is he moving at constant velocity? My guess is if the forces are balance on the bucket, then he will move at constant velocity because of the force he is applying on the other side of the rope (other wise he would be at rest)
Thanks!
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