Answer:
t=17.61 years.
Explanation:
Given that
Reserve of energy = 10,000 EJ
Energy used by human = 18 TW
We know that


So



Lets t time after energy will be exhaust
So



We know that
1 year = 365 days
1 year = 365 x 24 hr
1 year = 365 x 24 x 3600 s

So

t=17.61 years.
The time required for the moon to orbit around the earth is slightly longer than the earth rotation on its axis. The moon rotates in the same direction that the earth rotates on its axis. Thus, the moon's full rotation requires another 50min or 25 minutes per crossing of the earth's meridian.