A cable is strung between two walls 40 feet apart. The cable sags 30 inches. The cable has a breaking strength of 7000 pounds. How much weight will the center of the cable support before it breaks.
>>2888769Slightly less than the weight of your mother (approx 1700 lbs).
>>2888769Idk, use equation of parabola and figure out the angle at the center of the cable to determine the equation of the Y component of tension in the cable. The cable should break where the tension is most perpendicular to the y component. Or are we assuming the cable straightens out when it's loaded? You have to provide what kind of dumbass assumptions these stupid textbook questions use when they come up with these 'perfect world' scenarios. Also I forget if the tension force is half in this scenario since the vertical load is carried also by the reactionary tension force on the other half of the cable.
>>2888775The cables are going to support a heavy duty tarp with one inch of gravel on top of said tarp.
>>2888779The structure will be built using 2 - 30 foot long 14-18” trees trunks supported at 11 feet about foundation level. A 42’ tree trunk will be connected to the others on the east perimeter to maintain the 40’ seperation of them. On the south side a wall constructed with 2x10s and 6x6 posts will provide west side separation Cables will connect between the north and south sides and provide the support for a thick tarp. The tarp will be covered with a heavy substrate in order to counteract upward wind forces.
>>2888780Please film this when you do it because I want to see the absolute failure of whatever you're trying to build. My best advice would be to have a will and leave a suicide note.
Yeah man what in the sam hill is this about?What are you gonna do about the water that pools inside the tarp when it rains?
About 100lb. This will put about 700lb of tension on your cable. 700lb is the working load limit. It is a horrible idea and will break everything. Your structure will fail. Your cables will fail. Your tarp will fail. The gravel will fail. You are not smart enough to attempt this.
>>288880290% of the time these cockamamie scenarios are never followed up with an explanation of what OP is actually trying to accomplish.No mention of why 7000lb rope was chose, why 30" sag, where upward wind forces are coming from, no notion of safety factor.But still, I'm morbidly curious.
>>2888769a long sagging cable will ALWAYS break before you can pull it level. no exceptions. you cannot get the bow out of it without breaking it.
>>2888898At work there where some 140' long cables. They where supposed to be mostly flat. The client wanted them to be 2 inches higher in the center. It put an extra 1100lb of tension on the cable to raise it the extra 2 inches. Engineer signed off so all 43 cables went up 2 inches "flatter." We had to measure the tension on each cable and they where all around 2300lb.
>>2888898>>2889112That isn’t what OP is asking is it? >>2888769It looks like a textbook question to me. The equation is P=W/2*tan(a) so W=2Ptan(a) where tan(a) is 30in/40ft which is exactly 1/16 so you have to divide breaking strength over 8 making giving a super theoretical upper limit of 875lbs per cable.
>>2888779Tarp will fail first
>>2888769infinity weight, if the walls are 30 inches tall
Why the fuck are you using cables instead of some kind of joist system?
>>2888771>approx 1700 lbsThis. Or whatever it takes to pull the mollys out of your walls.
>>2888775technically it isn't a parabolaits hyperbolic or something
>>2889496Catenary arch, perhaps?
>>2888769Assume (pretend) the cables are not sagging. If Fc is limited to a max of 7000lb of force then Fw can be derived as 2 * 7000lb * 30" / √(30"^2 + (20'*12")^2) = 1736.48lb (rounding down b/c it's safer that way). Also assume a cable density of 0.118lb/ft that means 4.72lb I'm removing from your allowance this week.1731.76lb
>>2889520*meant to multiply the 20' by 12"/1', ignore that
>>288949790% this is like homework from a calculus class in the category arch page
>>2889520I’m confused. Where would shed go?
>>2889531Sorry, forgot that. Thanks for the catch.
