Why are black holes considered the "destroyers and creators" of life? A. Black holes play a role in the formation of galaxies that contain stars, which help planets form and (at least for Earth) support life; but they also can subsume celestial bodies and destroy life that passes the event horizon. B. Scientists have discovered that all known matter emanated from the first black hole in the universe, and that all matter will eventually return to be consumed by Sagittarius A*. C. All light in the universe originates from black holes, and light is necessary to support life, but too much light (as stars grow bigger and stronger) will destroy the life it created through fire. D. DNA is formed inside the center of a black hole and shoots out through the Schwarzschild radius, but when a black hole consumes a celestial object that has life on it, the DNA breaks down at the singularity.

The inside surface of a cylindrical-shaped cave of inner diameter 1.0 m is continuously covered with a very thin layer of water. the cave is very long and it is open on both ends. the water on the cave surface is at a constant temperature of 15.5 °c. the cave is constantly exposed to wind such that 15.5 °c air flows through the cave at 4.5 m/s. the kinematic viscosity of the air is 14.66 x 10-6 m2/s and the molecular diffusion coefficient of water vapor in the air is 0.239 x 10-4 m2/s. because the cave diameter is so large, the flow of wind down the length of the cave, in the x direction, can be treated like it is external flow and the cave surface can be approximated as flat where appropriate. calculate the x value, in a) the transition to turbulent flow occurs at rex meters, where the air flow transitions from laminar to turbulent along the inside surface of the cave b) calculate the x value, in meters, where the bulk steady state concentration of water vapor in the air flowing in the cave is 10% of the saturation concentration. assume the air at the surface of the water layer is 100% saturated with water vapor. assume the wind entering the cave contained no moisture before it entered the cave. take into account the transition from laminar to turbulent flow when solving part b