Answer
given,
mass of satellite = 545 Kg
R = 6.4 x 10⁶ m
H = 2 x 6.4 x 10⁶ m
Mass of earth = 5.972 x 10²⁴ Kg
height above earth is equal to earth's mean radius
a) satellite's orbital velocity
centripetal force acting on satellite = 
gravitational force = 
equating both the above equation



v = 5578.5 m/s
b) 


T = 14416.92 s

T = 4 hr
c) gravitational force acting


F = 5202 N
Answer:
a. a black hole
Explanation:
X-ray emission from the central degrees of the Milky Way Bright X-ray emission traces the coherent edge brightened shell-like feature, dubbed the northern chimney, located north of Sgr A* and characterized by a diameter of about 160 pc. On the opposite side, the southern chimney appears as a bright linear feature. Bright X-ray emission is observed at high latitude
Yo sup??
Average velocity=total distance covered/total time taken
total distance covered=4 + 8=12 miles
total time taken=6 hours
Therefore
average velocity=12/6
=2 miles/hour
Hope this helps