Gaseous co2 is contained in a vertical piston–cylinder assembly by a piston of mass 50 kg and having a face area of 0.01 m2 . the mass of the co2 is 4 g. the co2 initially occupies a volume of 0.005 m3 and has a specific internal energy of 657 kj/kg. the atmosphere exerts a pressure of 100 kpa on the top of the piston. heat transfer in the amount of 1.95 kj occurs slowly from the co2 to the surroundings, and the volume of the co2 decreases to 0.0025 m3 . friction between the piston and the cylinder wall can be neglected. the local acceleration of gravity is 9.81 m/s2 . for the co2, determine (a) the pressure, in kpa, and (b) the final specific internal energy, in kj/kg.

A6,600 kg train car moving at +2.0 m/s bumps into and locks together with one of mass 5,400kg moving at -3.0m/s. what is their final velocity? +0.50 m/s -1.0 m/s +2.5 m/s -0.25 m/s

Antireflective coatings on solar cells are often made by applying a thin film of silicon nitride (sinx), which has an index of refractive of 1.2, on the top of the silicon solar cell, which has a refractive index of about 3.5. however, the sun emits radiation of various wavelengths which the solar cell absorbs, and the antireflective coating can only absolutely minimize the reflection of one of these wavelengths. the coating thickness is chosen to reduce the reflection of green/yellow light (e = 2.2 ev), which is the most intense color in the solar spectrum (shown below). which of the following coatings would minimize reflection of green/yellow light? the answer is 820 nm how? what is the angular width of the central maximum of an electron traveling at 2 x 108 m/s going through a single slit of width 1 mm.

The air in an automobile tire with a volume of 2.60 ft3 is at 70°f and 21 psig. determine the amount of air that must be added to raise the pressure to the recommended value of 30 psig. assume the atmospheric pressure to be 14.6 psia and the temperature and the volume to remain constant. the gas constant of air is ru = 53.34ft⋅lbflbm⋅r(1 psia144 lbf/ft2) = 0.3704 psia⋅ft3lbm⋅r the amount of air that must be added to raise the pressure is lbm