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wakawu
Lv 5
wakawu asked in Science & MathematicsPhysics · 10 years ago

Tension in each cable physics 101?

http://i53.tinypic./ com/155pg10.png

totally forgot where to start with this. please see pic i uploaded above

2 tensions of cable connected through a weight via another singular cable. weight at end of string is 1000lbs. lengths of cable are given.

Update:

please copy + paste the link to an address bar to see it. for some reason i couldn't upload the link. you have to remove the space between the .com and tinypic. thanks!!

Update 2:

http://i53.tinypic./ com/4kg2gy.jpg

I knew something was missing... so I took the point of horizontal along where the three 'forces' meet, the 3 angles come out to 97, 128 and 135. and the angles between them along the horizontal and vertical axis are listed in the pic.

Again I can't seem to post the whole link so I left a space between tinypic and .com

2 Answers

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  • Ossi G
    Lv 7
    10 years ago
    Favorite Answer

    Hello

    This can not be solved, unless you have an angle between the cables, or of the cables with vertical or horizontal. or distance between the cables. The cables on your picture can have any positions.

    -------------

    Ok, take the angle between the red cable and the vertical, and the horizontal given as 45°.

    Then is the distance from the point where the 3 cables meet, to the ceiling = x = 9*sin45, and

    the angle of the other (black) cable with the vertical is cos^-1 ( x/11) = 9sin45/11 = 54.65°.

    -----

    To find the forces in the cables draw a parallelogram of forces:

    elongate the yellow cable upwards, and mark a distance from the uniting point of the cables of 1000 lbs. ( = 10 cm up, for instance , --> 1 cm = 100 lbs). Now draw parallels to the cables through this point. --> you get a parallelogram. The sides of the parallelogram are the forces in the cables with 1 cm = 100 lbs.

    You can calculate the magnitudes of the forces (i.e., the lengths of the sides of the parallelogram ) using the sine rule for triangles:

    the 2 congruent triangles (the parallelogram is divided by the vertical force vector into two congruent triangles) have angles 45°, 54.65°, and 80.34°.

    and 1000/sin80.34 = (Force red)/(sin54.65) = (Force black)/(sin45)

    Force red = 1000*sin54.65/sin80.34 = 827.36 lb

    Force black = 1000*sin45/sin80.34 =712.27 lb

    the force in the yellow cable is always = 1000 (lb)

    (is lb a force or a mass? I am not familiar with the lb/ft system, anyway, you know what to do)

    I hope it helps. I you do not understand me, mail me

    Regards

  • ?
    Lv 4
    4 years ago

    maximum suitable so some distance Sum forces in the horizontal on the element the place all 3 cables meet TR*cos30-TL*cos60=0 And in the vertical TR*sin30+TL*sin60-197.8=0 resolve the equations for the TR and TL

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