Answer:
Explanation:
v = Orbital speed = 130 km/s
d = Diameter = 16 ly
r = Radius = 
G = Gravitational constant = 6.67 × 10⁻¹¹ m³/kgs²
As the centripetal force balances the gravitational energy we have the following relation
Mass of the the massive object at the center of the Milky Way galaxy is
Free fall means rapid fall or a downward motion due to gravity. Sentence example: When Joe was accidentally bumped by Sarah, he was sent towards a free fall down the escalator, leading to a serious injury on his arm and two legs.
Apparently, the question is looking for A. electric potential energy;
but I don't think that's quite right. Electric potential difference is expressed in Joules / Coulomb which is the work to move a charge between 2 points
Example: If the electric field between, say, between 2 capacitor plates is
E = 100 Newtons / Coulomb then the work done in moving a unit of charge from the negative plate to the positive plate separted by 1 cm is
V = E * d = 100 Newtons / Coulomb * .01 meters = 1 Newton-meter / Coulomb
= 1 Joule / Coulomb which is the electric potential or potential difference
(The definition of electric potential between points is "the work moving a unit positive test charge from one point to the other")
Now in our above example where V = 1 Joule / Coulomb
if we move 10 Coulombs from the negative plate to the positive plate
W = V Q = 1 Joule / Coulomb * 10 Coulombs = 10 Joules
where work done has the correct units of Joules.
Your textbook should help clarify this.
