HW31 Due 20 Apr
1. Certain neutron stars (extremely dense stars) are believed to be rotating about 1 rev/s. If such a star has a radius of 20 km, what must be its minimum mass so that material on its surface remains in place during the rapid rotation? Solution
2. The Martian satellite Phobos travels in an approximately circular orbit of radius 9.4 x 106 m with a period of 7h 29m. Calculate the mass of mars based on this information. Solution
3. A projectile is fired vertically from the Earth’s surface with an initial speed of 10 km/s. Neglecting air drag, how far above the surface of the Earth will it go?
4. Find the pressure increase in the fluid in a syringe when a nurse applies a force of 42 N to the circular piston, which has a radius of 1.1 cm. Solution
5. Three liquids that will not mix are poured into a cylindrical container. The volumes and densities of the liquids are 0.5.L, 2.6gm/cc; 0.25L, 1.0 gm/cc; 0.40L, 0.8 gm/cc. What is the force on the bottom of the container due to these liquids? One liter equals 1000 cc. (Ignore the contribution due to the atmosphere.) Solution