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Forces on ropes connected to a slanted ceiling 
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#1
Dec3012, 07:05 AM

P: 28

Hey forum.
So I was posed the question whether the forces on two ropes will vary or not depending on if the ceiling from which they are hanging is slanted or not. Here's a picture depicting the scenario: I claim they'll equal 150 N respectively, independent of the ceiling slanting or not. But I am not sure how to motivate this (mathematically and/or conceptually). Do you guys have any idea? Picturesource: https://www.youtube.com/watch?v=hSQM0hoS6VE 


#2
Dec3012, 07:18 AM

Mentor
P: 41,456

Pretend the top of the picture was covered up so you had no idea about what the ropes attached to. Would it change your solution?
Do you know how to solve this problem in the first place? Assume a horizontal ceiling, if it helps. (Consider torques acting on the rod the girl hangs from.) 


#3
Dec3012, 08:14 AM

P: 28




#4
Dec3012, 08:17 AM

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P: 41,456

Forces on ropes connected to a slanted ceiling



#5
Dec3012, 08:52 AM

P: 28

But, if do have to consider torque, I am not really sure how the calculation really goes; care to show? 


#6
Dec3012, 01:27 PM

P: 1,478

SweatingBear
Is it the slant of the ceiling or the differing lengths of the two ropes that has you wondering? How does force transmit itself from one location on the rope to the next? Does the tension in a rope vary along its length? If the roof was so high that you could not tell whether the roof was slanted or not by just looking at it straight up to determine an incline, could you detemine the force at each end on the bar? 


#7
Dec3012, 02:15 PM

P: 1,368

Cut the girl vertically in half and attach each half to each end of each rope and remove the horizontal rod that she hangs from. The tension in each rope is the same regardless of the slope of the roof assuming equal halves.
Does this help? Sorry for the gruesome picture above. 


#8
Dec3012, 02:30 PM

P: 1,478

Great explanation  works for me. 


#9
Dec3012, 03:24 PM

P: 28

Concluding remark: Regardless of if the ceiling is slanted or not, the force on each rope is half of the persons weight i.e. 150 N (respectively). 


#10
Dec3012, 03:41 PM

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#11
Dec3012, 11:34 PM

P: 28




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