A rigid tank of volume 70 ft3, initially contains air at 14.7 lbf/in.2, 520oR. The tank is connected by a valve to a much larger tank containing air at 90 lbf/in.2, 520oR. The valve is opened and air flows slowly until the smaller tank achieves a pressure of 90 lbf/in.2and a temperature of 630oR. The air can be modeled as an ideal gas, and kinetic and potential energy effects can be neglected. For the contents of the smaller tank as the control volume, determine the heat transfer, in Btu. TABLE A-20E Ideal Gas Specific Heats of Som lemp. Air 40 0.240 0.171 1.401 100 0.240 0.172 1.400 200 0.2410.173 1.397 300 0.2430.1741.394 400 o.245o.1761.389 500 o.248 o.1791.383 600 o.250 o.182 1.377 700 o.254 0.185 1.371 800 0.257 0.188 1.365 900 o.2590.1911.358 1000 o.263 0.1951.353 1500 o.276o.2081.330 2000o.286o.2171.312

What is the relationship between atmospheric pressure and the density of gas particles in an area of increasing pressure? (2 points) as air pressure in an area increases, the density of the gas particles in that area decreases. as air pressure in an area increases, the density of the gas particles in that area increases. as air pressure in an area increases, the density of the gas particles in that area remains constant. as air pressure in an area increases, the density of the gas particles in that area increases and decreases in an alternating pattern. 3. which of the following correctly describes a way in which earth's atmosphere interacts with the geosphere? (2 points) it contains gases that living organisms breathe. it contains gases that trap incoming solar radiation. it provides a medium for cycles that provide nutrients to living organisms. it provides a medium for water to move between earth's surface and the air. 4. which of the following is considered a drawback to using wind energy as a source of power? (2 points) wind energy is nonrenewable. wind energy produces large amounts of air pollution. wind turbines can kill birds that fly through the rotors. wind turbines are built too close to major population centers. 5. a meteorologist predicts that the weather in a region will soon change from clear skies to probable thunderstorms. prior to making this prediction, what did the meteorologist most likely observe on a barometer? (2 points) the barometer fell slightly. the barometer fell substantially. the barometer rose slightly. the barometer rose substantially. 6. which of the following do meteorologists not typically use weather balloons to record? (2 points) atmospheric pressure cloud types humidity temperature 7. during which step in the can crush lab did water vapor force air from the can? (2 points) the can was filled nearly to the top with water. the can was placed on the hot stove top burner for several minutes. the can was removed from the hot stove top burner. the can was placed upside-down in the water-filled pan.

In positive numbers less than 1, the zeros between the decimal point and a non-zero number are blank significant

(a) assume the equation x = at^3 + bt describes the motion of a particular object, with x having the dimension of length and t having the dimension of time. determine the dimensions of the constants a and b. (use the following as necessary: l and t, where l is the unit of length and t is the unit of time.) (b) determine the dimensions of the derivative dx/dt = 3at^2 + b. (use the following as necessary: l and t, where l is the unit of length and t is the unit of time.)