Three Problems in Astrophysical Dynamics

Three dynamical problems in astrophysics are attacked. These are: 1. Radiation Pressure on Dust Grains near the Galactic Center, It is shown that radiation pressure may drive interstellar dust grains out of the galactic center. This explains the observed density distribution of dust in this region, 2. The Acceleration of Shock Waves in the Atmospheres of Cool Mira Variable Giants, It is shown that shocks may accelerate as they propagate outward, but not indefinitely. They reach a terminal velocity which is approximately 25 km s-1 for stars with surface temperatures cooler than 2400 K, and 3. Violent Relaxation and the Infall of Gas into Cluster of Galaxies. The infall problem is reviewed with the inclusion of the time dependence of the gravitational field. The controversy over the temperature distribution of the gas after infall is resolved. Thus the constraint on the contribution of the gas outside of clusters of galaxies toward the total density of the universe is restored to Ωg < .1.