Originally Posted by **Tygra** Actually could I have some further guidance, as I am bit stuck where to start? Could someone start me off. I need some more explantion of how cable thickness increases with length/height with formulas etc. |

I suggest starting with an equation for stress in the cable. At the top of the elevator shaft the cable supports weight equal to the weight of the elevator car plus the weight of the cable, and so the stress in the cable is the sum of those two elements divided by the cross-sectional area of the cable.. The weight of the elevator car is a constant, say $\displaystyle W_c$. The weight of the cable is its length times its cross-section area times the density of the cable material $\displaystyle \rho $. So:

Stress = $\displaystyle \sigma = \frac {(W_{car} + W_{cable})}{A} = \frac {(W_{car} + LA \rho g )}{A} $

Rearrange to solve for A, and you'll see that the factor L in the denominator causes A to increase to infinity as L approaches $\displaystyle \frac {\sigma _{max}}{ \rho g} $