1. In Star Trek: Deep Space Nine everyone lives on a giant circular space station. To maintain gravity, the station spins. The diameter of the outer ring of the station is 1451m. What must the angular velocity be for a person in outer ring of the station to experience 1g of gravity? (25 points)

Why are some galaxies’ spectra blueshifted rather than redshifted? question 4 options:

Asheet of steel 1.5 mm thick has nitrogen atmospheres on both sides at 1200oc and is permitted to achieve a steady-state diffusion condition. the diffusion coefficient for nitrogen in steel at this temperature is 6 x 10- 11 m2 /s, and the diffusion flux is found to be 1.2 x 10-7 kg/m2 -s. also, it is known that the concentration of nitrogen in the steel at the high-pressure surface is 4 kg/m3 . how far into the sheet from this high-pressure side will the concentration be 2.0 kg/m3 ? assume a linear concentration profile.

How many excess electrons must be present on each sphere if the magnitude of the force of repulsion between them is 4.57×10−21 newtons?