An astronaut on the moon throws a wrench straight up at 4 0 m/s. Three seconds later it falls downwards at a velocity of 0.80 m/s.

What is the final velocity when the wrench leaves the astronaut's hand.

(its not 0m/s btw)

1 answer

v(t) = 4.0 - gt
we have v(3) = -0.8, so
4 - 3g = -0.8
g = 1.6 m/s^2 on the moon

Not sure just what you are asking, but that's the only thing I see unanswered.