7. A planetary nebula is a cloud of mainly hydrogen gas with density ρ of 1000.0 molecules per cubic centimeter, and a temperature T of 10,000 K. What is the pressure of the gas in the nebula? ___(8)___ (Pa)

5. The following metal objects, a disk, a solid sphere, a hollow sphere, and a loop have the same radius and mass. Assuming they are released from the same point on a ramp at rest and start rolling down, which one will take the shortest time to reach the bottom of this ramp? ___(6)___