How high is the building in meters? In feet?

Question

An object is dropped from the top of a building into a pool of water at ground level. There is a splash 6.8 sec. after the object is dropped.

Answer 1

u= 0, t= 6.8sec, a= 9.81 m/s2

s= ut+0.5at^2

s= 0+0.5 (9.81) (6.8)^2

  = 227 m

  = 745 ft

Answer 2

Kinematics:

Vi = 0 m/s

g = 10 m/s^2

t = 6.8s

we want distance, x

x = (1/2)gt^2

x = (1/2)(10)(6.8)^2

x = 231.2 meters but that doesnt take significant figures into account.

Answer 3

Well, i might be wrong on that, but if it  a free falling object falls at 9.8 meters per second squared; after 6.8 second the object has travelled 453.15 meters or 1486.71 feet.

Answer 4

Well,  I realize the fist answerer said his final result didn't take significant figures in to account, but if you are going to round g to 1 significant figure, you really shouldn't give the answer to 4 figures. Also since the input data has 2 significant figures has two significant figures, one should use at least 2 for g as well

Using the "g" constant built into my calculator, (9.80665) I get 226.7 using four figures, but rounded to 2 significant figures it is 230m, (which is the same as you get rounding the first answer to 2 figures, still I think using at least 2 figures for g would be a good idea). If one does the conversion to feet using the intermediate 4 (or more) significant figures, rounding after the conversion I get 740feet (rounded to 2 figures) , but if one converts 230m to feet I get 750

However the first answer did use the proper formula and is far closer than the second answer, apparently the second person forgot that the object started at 0 velocity, and just used 9,8 * 6.8^2