If an arrow is shot straight upward on the moon with a velocity of 73 m/s, its height (in meters) after t seconds is given by s(t) = 73 t - 0.83 t^2.

Question

If an arrow is shot straight upward on the moon with a velocity of 73 m/s, its height (in meters) after t seconds is given by s(t) = 73 t - 0.83 t^2. 
(A) What is the velocity of the arrow (include units) after 5 seconds?
(B) How long will it take for the arrow to return and hit the moon (include units)?
(C) With what velocity (include units) will the arrow hit the moon?