A gravity dam as shown in the figure with a top width $20$ m $,$ bottom width $100$ m and is $100$ m high. Determine the factor of safety against sliding and overturning moment if $=0\mathrm{.}45.$

Use unit weight of concrete $=23\mathrm{.}54$kN$/$cu$.$m

the unit weight of water $=9\mathrm{.}81$kN$/$cu$.$m