A couple of questions that Im struggling with again...that I really need to figure out ASAP(adsbygoogle = window.adsbygoogle || []).push({});

On the way to the Moon the Apollo astronauts reached a point where the Moon's gravitational pull became stronger than the Earth's.

(a) Determine the distance of this point from the center of the Earth.

(b) What is the acceleration due to the Earth's gravity at this point?

I have this set up (7.36e22)/(.38e9-x)^2 = (5.98e24)/x^2

and i get 1.11x = .38e9 and yea im lost from there....any help there? and once i get the radius i can get part b with GMe/R^2

and a couple more on Satelite Motion...

Plaskett's binary system consists of two stars that revolve in a circular orbit about a center of mass midway between them. This means that the masses of the two stars are equal (Fig. P14.15). If the orbital velocity of each star is 220 km/s and the orbital period of each is 20.4 days, find the mass M of each star. (For comparison, the mass of our Sun is 1.99e30 kg.)

v = 2pir/T

220000 m/s = 2pir/ (1762560)

r = 6171443003 m? and mv^2/r = G2m/R

and thats where i'm lost...

and my last question....

Neutron stars are extremely dense objects that are formed from the remnants of supernova explosions. Many rotate very rapidly. Suppose that the mass of a certain spherical neutron star is twice the mass of the Sun and its radius is 9.0 km. Determine the greatest possible angular speed it can have for the matter at the surface of the star on its equator to be just held in orbit by the gravitational force.

Im completely drawing blanks on this one....

r = 9000 m, m = 4e30....and how exactly do i get angular speed? really lost...

thanksssssss a lot for any and all help

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# Homework Help: Universal Gravitation and Satelite Motion

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