To solve for this we need to use the formula P = W/T (Power = Work/Time).
Since we do not have time, we shall switch up the formula.
Our new formula is T = W/P (Time = Work/Power).
We have 1,800,000 J of work, and 15,000 W of power.
1,800,000/15,000 = 120.
It will take 120 (insert measure of time here).
I hope this helps!
To solve the problem it is necessary to use the concepts of Orbital Speed considering its density, and its angular displacement.
In general terms the Orbital speed is described as,

PART A) If the orbital speed of a star in this galaxy is constant at any radius, then,




PART B) This time we have
, where
is the angular velocity (constant at this case)




PART C) If the total mass interior to any radius r is a constant,




Answer:
Organisms and their environment
(a) The stone moves by uniform accelerated motion, with constant acceleration

directed downwards, and its initial vertical position at time t=0 is 750 m. So, the vertical position (in meters) at any time t can be written as

(b) The time the stone takes to reach the ground is the time at which the vertical position of the stone becomes zero: y(t)=0. So, we can write

from which we find the time t after which the stone reaches the ground:

(c) The velocity of the stone at time t can be written as

because it is an accelerated motion with initial speed zero. Substituting t=12.37 s, we find the final velocity of the stone:

(d) if the stone has an initial velocity of

, then its law of motion would be

and we can find the time it needs to reach the ground by requiring again y(t)=0:

which has two solutions: one is negative so we neglect it, while the second one is t=11.78 s, so this is the time after which the stone reaches the ground.
Logitudinal waves are the waves which displacement of the medium is in the same direction as , or oppositemdirection to ,the direction of propagation of the wave.