Analysis of Cables

To find tension at extreme points of cable/at support:

T = $R_A$ = $√{{A_x^2}+{A_y^2}}$

tan θ = ${A_y}/{A_x}$

For finding other tensions use Lami’s theorem at intermediate joints

To find sag at any point



Use geometry for example, ${A_y}/{A_x} = {\text"Verticle distance/sag"}/{\text"Horizontal distance"}$

Important tips

1. Observe number of unknown forces. If no. of unknown forces is ‘n’ then consider (n-3) parts of cable for finding the unknown quantities.

2. While selecting no. of parts care should be taken that parts must be starting from “same support” upto the points where sags of points are known.

3. Although the tensions in different portions of the cable are different but their horizontal components are equal.