Ahole of diameter d = 0.25 m is drilled through the center of a solid block of square cross section with w = 1 m on a side. the hole is drilled along the length, l = 2 m, of the block, which has a thermal conductivity of k = 150 w/m ⋅ k. the four outer surfaces are exposed to ambient air, with t[infinity],2 = 25°c and h2 = 4 w/m2 ⋅ k, while hot oil flowing through the hole is characterized by t[infinity],1 = 300°c and h1 = 50 w/m2 ⋅ k. determine the corresponding heat rate and surface temperatures.

An insurance company wants to know if the average speed at which men drive cars is higher than that of women drivers. the company took a random sample of 27 cars driven by men on a highway and found the mean speed to be 72 miles per hour with a standard deviation of 2.2 miles per hour. another sample of 18 cars driven by women on the same highway gave a mean speed of 68 miles per hour with a standard deviation of 2.5 miles per hour. assume that the speeds at which all men and all women drive cars on this highway are both approximately normally distributed with unknown and unequal population standard deviations.

6–55 refrigerant-134a enters the condenser of a residential heat pump at 800 kpa and 358c at a rate of 0.018 kg/s and leaves at 800 kpa as a saturated liquid. if the compressor consumes 1.2 kw of power, determine (a) the cop of the heat pump and (b) the rate of heat absorption from the outside air.

Which is the best predictor of the radioactive nature of an isotope? o the proton-to-electron ratio the neutron-to-proton ratio o the neutron-to-electron ratio the electron-to-proton ratio