Weight Suspended by Two Cables

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This Demonstration calculates the tension forces in two cables that support a weight.


Select equal cable lengths and the tension is the same in each cable; the tension changes as a slider changes the angle between the cables.

Select unequal cable lengths and the tension in the cables is different. Changing the angle of each cable to the horizontal with a slider changes the cable length.

Change the mass of the ball with a slider.


Contributed by: Rachael L. Baumann (September 2017)
Additional contributions by: John L. Falconer
(University of Colorado Boulder, Department of Chemical and Biological Engineering)
Open content licensed under CC BY-NC-SA



For equal cable lengths, a force balance in the direction is done to determine the cable tension:


rearranging to solve for tension:


where is tension (N),

is the angle (degrees),

is the mass of the ball (kg) and

is acceleration due to gravity.

When the cable lengths are unequal, force balances in the and directions are done to calculate the tension forces in each cable:


where and are the tensions in the left and right cables (N), and and are the angles of the left and right cables (degrees).

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