Number 4 is c , number 5 is a , number 6 is d and 7 is a
OK.
But first we need to know . . .
-- Where is Riverdale ?
-- What is the air temperature there right now ?
-- What kind of system is being used now ?
-- Where can we get a complete description of the groundwater system ?
Answer:
a) Yes, there are
shakes in a second (
) in a year there are 31,536,000 seconds... that is 3.1536x
(
)
b) Note that the defined universe day will have 60*60*24=86400 universe seconds if the seconds are defined as normal seconds.
Also one universe day (or 86400 universe seconds) is equivalent to 1010 years. Now using a rule of three we can know the seconds that humans have existed.

That is about 2 and half hours.
It depends on Mass and velocity
The answer is c. velocity