Question

thermodynamics

4. (9 points) Assume that Morgantown has a cylindrical water storage tower of the height 15 m and diameter 10 m. Please find the gauge and absolute pressure at the bottom of the tank, and the force acting on the bottom of the tank, if the water density is 1,000 kg/m3. 5. (9 points) Neil Armstrong weighted about 650 N on the Earth. Please calculate (5a). (3p) his mass. (5b). (3p) his weight on the Moon, where the acceleration of gravity is 1.62 N/kg. (5e). Gp) his weight on the Apollo 11 spacecraft, where the acceleration of gravity was 66 N/kg 6. (8 points) The mass of air in our classroom is assumed to be known, 870 kg. Approximating the room by a cuboid of length 15m, width 10 m and height 5 m, please find the density, specific volume, and specific weight of the air in the room.

Answer 1

$gauge\;pressure\;dP=\rho\times\;g\times\;h=1000\times10\times15=1.5\times10^5\;Pa\\\\\\absolute\;pressure\;P=\;p_o+dP=10^5+1.5\times10^5=3.5\times10^5\;Pa\\\\\\5)\\\\mass\;m=\frac{W_{earth}}{g_{earth}}=\frac{650}{9.8}=66.33\;Kg\\\\\\(ii)\\\\W_{moon}=m\times g_{moon}=107.45 N\\\\(iii)\\W_{apollo}=66.33\times 6.6=438\;N\\\\\\(6)\\\\Density=\frac{mass}{volume}=\frac{870}{15\times10\times5}=1.16\;kg/m^3\\\\specific\;volume=\frac{V}{m}=0.862\;m^3/kg\\\\\\specific\;weight=\frac{mg}{V}=\frac{870\times9.8}{15\times 10 \times5}=11.4\;N/m^3$