7. A 75 kg astronaut orbits the moon at a distance of 2.5 X 106 m from its center. (Mass of moon = 7.35 x 1022 kg) at. What is the force acting on the astronaut by the moon? b. How fast is the astronaut orbiting around the moon? 8. A piece of copper has a mass of 5.2 kg. a. What is the volume of this piece of copper? b. The copper is then totally submerged in water. What is the buoyant force acting on it? c. What is the piece of copper's apparent weight in the water?9. Water flows in a horizontal pipe at a velocity of 8 m/s with a pressure of 150000 Pa. The pipe has a cross sectional area of 0.05 square meters. a. If the pipe widens to an area of 0.08 square meters, what will be the velocity of the water through this section of the pipe? b. What is the pressure through this section of the pipe?10. A 2.5 kg mass is attached to the end of a horizontal spring of spring constant 60 N/m and set into simple harmonic motion with an amplitude of 0.5 m. a. What is the maximum potential energy of the system? b. What is the frequency of Vibration? c. What is the period of Vibration