3. a 2.5 mm thick steel pipe (diameter 25 cm) transports nitrogen gas at a temperature of 500°c. in any 10 cm section of the pipe, nitrogen atoms are "lost" into the external environment at a rate of 7.5 x 108 atoms/s. if the nitrogen concentration at the exterior pipe surface is 1.5 x 1012 atoms/cm3, find the nitrogen concentration at the interior pipe surface. the diffusion constants for nascent nitrogen in steel are do = 0.003 cm2/s, q = 76.1 kj/mol and r = 8.314 j/k·mol.

There is a theory that indicates that dinosaurs became extinct when about 65 million years ago, a large asteroid hit the earth surface. dust caused by this collision blocked the sunlight reaching the earth's surface and many forms of life became extinct due to the cold. fearing this threat, how large the radius of an asteroid should you be looking for if the dangerous asteroid size is approximately the same as the one that killed the dinosaurs? available data suggests that about 18% of that asteroid's mass ended up as a dust spread evenly over earth after eventually settling out of the upper atmosphere. about 0.0180 g/cm^2 of dust, which is chemically different than the earth's rock, covered the earth's surface. typical asteroids have a density of about 1.9 g/cm^3. now that we know the size of the asteroid, how much energy was released during impact, assuming all of it was just the kinetic energy of the asteroid right before the impact?

Gordon is going for a run through the park, but it is cold outside. the low outside temperature could affect his personal safety.

The average density of the planet uranus is 1.27 103 kg/m3. the ratio of the mass of neptune to that of uranus is 1.19. the ratio of the radius of neptune to that of uranus is 0.969. find the average density of neptune.