A massive stone pillar `20 m` high and of uniform cross section rests on a rigid base and supports a vertical load of `5.0 xx 10^(5)N` at its upper end. If the compressive stress in the pillar is not exceed `16 xx10^(6)N//m`, what is the minimum cross-sectional area of the pillar? (Density of the stone `=2.5xx10^(3) kg//m^(3)` take `g= 10 N//kg)`

Options

A. `0.15m^(2)`
B. `0.25m^(2)`
C. `0.35m^(2)`
D. `0.45m^(2)`

Answer

D

Explanation

`(20axx2.5xx10^(3)xx10+5xx10^(5))/a=1.6xx10^(6)`
or `500a+500=1600a`
or `100a=500` or `a=5/11m^(2)=0.45m^(2)`