Show that keplerian rotation implies ~ ~ r-1/2. use kepler's third law: p2 ~ ay and assume perfectly circular orbits (i. e. write the rotation speed in terms of p and a) (b) show that a spherically symmetric mass distribution with constant density gives solid body rotation (v = const x r). (set the centripetal force on a star in a circular orbit equal to the gravitational force on that star and substitute for m in terms of the uniform density.)

Consider an ordinary, helium-filled party balloon with a volume of 2.2 ft3. the lifting force on the balloon due to the outside air is the net resultant of the pressure distribution exerted on the exterior surface of the balloon. using this fact, we can derive archimedes’ principle, namely that the upward force on the balloon is equal to the weight of the air displaced by the balloon. assuming that the balloon is at sea level, where the air density is 0.002377 slug/ft3, calculate the maximum weight that can be lifted by the balloon. note: the molecular weight of air is 28.8 and that of helium is 4.

Hydrogen and helium are both members of?

Which subatomic particle has a negative charge