Answer
$W=8.370\times10^{3}lb$
Work Step by Step
Height of the pillar $h=2.2m$
Radius of pillar $r=0.50m$
Volume of the cylindrical pillar $V=\pi r^2 h$
$v=3.14\times (0.50m)^2\times2.2m$
$V=1.727m^3$
Density of concrete is given as $\rho =2.2\times10^{3}kg/m^3$
from $\rho=\frac{M}{V}$
$M=\rho V$
so mass of the concrete used is $M=2.2\times10^{3}kg/m^3\times 1.727m^3$
$M=3.7994\times10^{3}kg$
taking acceleration due to gravity as $g=9.8m/s^2$
weight of concrete $W=Mg$
weight of concrete $W=3.7994\times10^{3}kg\times9.8m/s^2$
weight of concrete $W=37.23412\times10^{3}N$
weight of concrete $W=3.723412\times10^{4}N$
now since $1N=0.2248lb$
so weight of concrete $W=3.723412\times10^{4}\times 0.2248lb$
so weight of concrete $W=0.8370\times10^{4}lb$
weight of concrete $W=8.370\times10^{3}lb$
