The energy flux associated with solar radiation incident on the outer surface of the earth’s atmosphere has been accurately measured and is known to be 1368 W/m2. The diameters of the sun and earth are 1.39 × 109 and 1.27 × 107 m, respectively, and the distance between the sun and the earth is 1.5 × 1011 m. (a) What is the emissive power of the sun? (b) Approximating the sun’s surface as black, what is its temperature? (c) At what wavelength is the spectral emissive power of the sun a maximum? (d) Assuming the earth’s surface to be black and the sun to be the only source of energy for the earth, estimate the earth’s surface temperature.

Aloaded platform of total mass 500 kg is supported by a dashpot and by a set of springs of effective stiffness 72 kn/m. it is observed that when the platform is depressed through a distance x = 12.5 cm below its equilibrium position and then released without any initial velocity; it reaches its equilibrium position in the shortest possible time without overshoot. find the position and velocity of the loaded platform 0.10 sec. after its release. if a further load of 400 kg is added to the platform, find, i) the frequency of damped vibrations, and i) the amplitude of vibration after 2 complete oscillations, given that the initial amplitude is 15 cm.

Fluids at rest possess no flow energy. a)- true b)- false

Different types of steels contain different elements that alter the characteristics of the steel. for each of the following elements, explain what the element does when alloyed with steel.