(a) 
The gravitational potential energy of the two-sphere system is given by
(1)
where
G is the gravitational constant
is the mass of sphere A
is the mass of sphere B
r = 1.8 m is the distance between the two spheres
Substitutign data in the formula, we find
and the sign is negative since gravity is an attractive force.
(b) 
According to the law of conservation of energy, the kinetic energy gained by sphere B will be equal to the change in gravitational potential energy of the system:
(2)
where
is the initial potential energy
The final potential energy can be found by substituting
r = 1.80 m -0.60 m=1.20 m
inside the equation (1):
U=-\frac{(6.67\cdot 10^{-11})(94 kg)(100 kg)}{1.2 m}=-5.22\cdot 10^{-7} J
So now we can use eq.(2) to find the kinetic energy of sphere B:
The answer for this question would be Planetary Nebula.
Black holes are created when the star core has a mass of more than 2.5 times of the Sun. In Supernova, fo<span>r stars with mass of more than 8 times the mass of the Sun, death is signalled by a gigantic explosion: during the first second it can be as bright as a whole galaxy with hundreds of billions of stars. In Red Giants, it is </span>due to explosion of average stars like the Sun. Lastly, in Planetary Nebula, f<span>or small stars (that is less than 8 times the mass of the Sun), at the end of the Red Giant phase, the star can’t contract enough to generate the temperatures needed for further nuclear fusion.</span>
Answer:
45 kg is the mass of a table that weights 441 newton.
