Balancing.
When the same force is applied from both sides,the forces cancel out each other.
According to Stefan-Boltzmann Law, the thermal energy radiated by a radiator per second per unit area is proportional to the fourth power of the absolute temperature. It is given by;
P/A = σ T⁴ j/m²s
Where; P is the power, A is the area in square Meters, T is temperature in kelvin and σ is the Stefan-Boltzmann constant, ( 5.67 × 10^-8 watt/m²K⁴)
Therefore;
Power/square meter = (5.67 × 10^-8) × (3000)⁴
= 4.59 × 10^6 Watts/square meter
A. 
The orbital speed of the clumps of matter around the black hole is equal to the ratio between the circumference of the orbit and the period of revolution:

where we have:
is the orbital speed
r is the orbital radius
is the orbital period
Solving for r, we find the distance of the clumps of matter from the centre of the black hole:

B. 
The gravitational force between the black hole and the clumps of matter provides the centripetal force that keeps the matter in circular motion:

where
m is the mass of the clumps of matter
G is the gravitational constant
M is the mass of the black hole
Solving the formula for M, we find the mass of the black hole:

and considering the value of the solar mass

the mass of the black hole as a multiple of our sun's mass is

C. 
The radius of the event horizon is equal to the Schwarzschild radius of the black hole, which is given by

where M is the mass of the black hole and c is the speed of light.
Substituting numbers into the formula, we find

Answer:
1788.402 MJ
Explanation:
Work done = Force (N) x distance (m)
First we have to convert distance into metres:
173.8 x 1000 = 173,800 m
Then plug these values into the equation above:
173,800 x 10290 = 1788402000 J
The reason it's Joules (the unit for energy) is because work done = energy transferred
Now we have to convert Joules into Mega Joules:
1 J = 1/1000000 MJ
1788402000 J = 1788402000/ 1000000 = 1788.402 MJ
A) heterogeneous mixture & I believe B?
I know A is correct though