Wednesday, October 29, 2008
HW: Hints for 5.70
This problem is a "mechanical advantage" problem. Here is a hint question to help you, if you are unsure about this problem. How many ropes are pulling the load, effectively? In other words, if the tension of the rope that the worker is pulling is T, what is the effective force that the rope is applying to the pulley? If you do not know the answer to this one for sure, consider the free body diagram for the pulley. You may ignore the mass of the rope (implicit assumption here) and may draw a small rectangle that tightly fits the pulley. If you do so, you may consider all things included in that rectangle as a single compound object. Or, even more simply, you may draw a bigger rectangle that encloses the pulley and the load, and consider all objects inside that rectangle as a single compound object as heavy as the load (again, assuming other things do not weigh any at all).
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2 comments:
Thanks this was actually really helpful two ropes huh very tricky...
Also I just realized but although there is only 1 rope there are two sections of the rope that can hold 460 N. The first being between the construction worker pulling up and the other between the rope and the ceiling. Both of these carry tension in separate parts of the rope so theoretically m*g=460N/g= the mass of about 46 kg if we use g as 10. so.. 46 kg is about how much teh Tension can hold but remember there are two separate tensions on the rope so at the moment with how the diagram is set up each 46 kg * 2 = about 92 kg it would be able to hold.
By the way sorry if I didn't explain this very clearly.
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