Physics
posted by Jennifer .
Robin Hood is walking through Sherwood Forest when he comes upon Sheriff of Nottingham. The Sheriff tells Robin Hood that he is going to arrest hum for numerous misdeeds. Robin pulls out his bow, loads an arrow, puls the bow back 0.70 m, and shoots an arrow into the Sheriff's hat, knocking the hat with the arrow lodged in it off his head. The hat's mass is 0.5 kg. It takes 4 N to pull Robin's bow back 0.10 m, and the arrow has a mass of 0.20 kg. (A) What is the speed of the hat with the arrow in it just fter it is struck? Assume the arrow travels horizontally between Robin and the Sheriff and neglect air resistance. (B) If the Sheriff is 2.0 m high, how far behind him will his hat with the arrow in it hit the ground?
I found the answer to (A) to be 2.8 m/s how do I get (B)?

Yes, I get 2.83 m/s for A
Object of mass m (which happens to be .7 kg but it will not matter) is travelling horizontal at 2.83 m/s NO vertical speed yet but 2 m high.
How long will it take to fall to the ground?
d = 2 = (1/2) (9.8) t^2
t^2 = .408
t = .639 seconds to landing
How far did it go horizontal at 2.83 m/s for .639 s?
distance horizontal = 1.80 m 
how did you get 2.8 m/s for A?