6. Determine the mass and the weight of the air contained ina room whose dimensions are 6 m _ 6 m _ 8 m. Assume the density of the air is 1.16 kg/m3. 9. The constant-pressure specific heat of air at 25°Cis 1.005 kJ/kg °C. Express this value in kJ/kg-K. J/g °C,kcal/kg-°C, and Btu/lbm-°F. 13. A 4-kW resistance heater in a water heater runs for2 hours to raise the water temperature to the desired level. Determine the amount of electric energy used in both kWhand kJ. 38. The temperature of water changes by 10°F during aprocess. Express this temperature change in Celcius (°C),Kelvin (K), and Rankine (R) units. 49. The water in a tank is pressurized by air, and the pressureis measured by a multifluid manometer as shown in Fig. Pl-53. Determine the gage pressure of air in the tank if/;, = 0.2 m, h2 = 0.3 m, and h3 = 0.46 m. Take the densities of water, oil, and mercury to be 1000 kg/m3, 850 kg/m3, and13,600 kg/m3, respectively.