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Vector mechanics problem 
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#1
Jan1813, 09:14 PM

P: 21

Okay so I am stuck on this problem.
A moveable bin and its contents have a combined weight of 2.8 kN. Determine the shortest chain sling ACB that can be used to lift the loaded bin if the tension in the chain is not to exceed 5 kN. So the picture given is a crate with h = 0.7m and base 1.2m with the corners labeled A and B. Point C is above, centered of the crate between A and B with the connected chain to another. Point C is the location of interest being as this is where all the forces are acting. My problem lies within finding this shortest length for the chain sling. I have drawn my FBD by trying to resolve my forces into components, I just lack the values for the angles. I'm sure with some basic geometry I will get this values. Also since I am dealing with a max force, am I to assume that the vertical force acting along the yaxis of point C is to be the 5 kN? If anyone can give some advice, I would be greatly appreciative. I do not need an answer drawn out, just a little motivation that I am on the right track. Thanks! 


#2
Jan1813, 09:35 PM

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In order to lift the bin, the is a minimum total vertical force. What is it? What other forces contribute to the tension? 


#3
Jan1813, 09:55 PM

P: 21

As for the forces acting at point C, there would be the two tensions, AC & BC and the upward force acting at this point. I feel like I am neglecting the gravitational force of the bin though? 


#4
Jan1813, 10:12 PM

P: 21

Vector mechanics problem
Okay I have figured it out now. I found that point C the weight of the bin is evenly distributed as vertical force components to AC and BC. Then the angle formed by the chain from the horizontal, or the hypotenuse, then takes on the max value of 5 kN. Hereafter, the angle that the chain forms can be used with the dimensions of the bin to find out what the shortest chain length, ABC, can be.
I have to say this one was a bit tricky. Thanks for your help Simon Bridge. 


#5
Jan1813, 11:14 PM

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Well done. They can get trickier than that ;)



#6
Jan1813, 11:32 PM

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Welcome to Physics Forums, and just so you know for the future, we have separate forums for getting help with exercises like this one, regardless of whether they're school assignments or just for your own benefit. Look at the subforums of "Homework and Coursework Questions":
http://www.physicsforums.com/forumdisplay.php?f=152 Please post future questions like this, in one of those forums. 


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