the following are solutions to the diffusion equation expadt - er co specify the best solution for each of the following examples and explain your choice a thin sheet of steel (thickness 0.8 mm) with a high carbon concentra- tion is annealed in a carbon-free gas environment for 2 weeks. the dif- fusion coefficient of c in steel is 10-7 cm2/s a) b) agas containing a dopant is passed over a si wafer with thicknes: s 0.1 cm for 30 minutes. the dopant diffusion coefficient is 10-10 cm2/s a thin film of radioactive fe is deposited on the and of a 40 mm long fe cylinder and annealed at high temperature temperature for 60 minutes the diffusion coefficient of fe at this temperature is 10-9 cm2/s c)

The lights used by mark watley (played by matt damon) during the film the martian seem to be metal halide lamps. metal halide lamps are filled with vaporized mercury and metal-halogen compounds. when an electric current is passed through the lamp, the tube begins to glow a bright white/blue color. if you were to pass this light through a prism to separate the individual light frequencies, you would see a rainbow just as you would if using natural sunlight because of the complexity of the metal halide gas and the vast amount of possible electron transitions. (the study of light in this way is known as spectroscopy and allows astronomers to know exactly what atoms compose distant stars, simply by looking at the light they emit. the spectral lines an atom produces uniquely identifies that atom just like a fingerprint uniquely identifies a person. the momentum equation and energy equation that we have used above can be combined to give the following equation: c = e p where again p is the phonon momentum, e is the photon energy and c is the speed of light. when you divide the photon energy found in #6 by the photon momentum found in #4, do you get the speed of light? (if not, check your work for questions #4 through #6). yes no

Which graph represents motion with an object with positive velocity that is located at a position of 3 meters at a time of 0 seconds? a) a b) bb eliminate c) c d) d

The star betelgeuse is about 600 light-years away. if it explodes tonight, a. we'll know because debris from the explosion will rain down on us from space.b. we'll know it immediately because it will be brighter than the full moon in the sky.c. we won't know about it until 600 years from now.d. none of the above.