A60-gallon water heater is initially filled with water at 50°f. determine how much energy [in btu) needs to be transferredto the water to raise its temperature to 120‘f. evaluate the water properties at an average water temperature of 85°f.

Consider a large isothermal enclosure that is maintained at a uniform temperature of 2000 k. calculate the emissive power of the radiation that emerges from a small aperture on the enclosure surface. what is the wavelength ? , below which 10% of the emission is concentrated? what is the wavelength ? 2 above which 10% of the emission is concentrated? determine the wavelength at which maximum spectral emissive power occurs. what is the irradiation incident on a small object placed inside the enclosure?