Question

A penny is dropped from the top of a building 310 m high. Ignoring air resistance, if the penny falls straight down, with what speed would it hit the ground?

Answer 1

how long does it take to fall?

4.9t^2 = 310

so, its downward speed is

v = 9.8t

Answer 2

Since the object is in free fall, it experiences uniformly accelerated motion (UAM). We can use the formula:
vf^2 - vo^2 = 2gd
where
vf = final velocity
vo = initial velocity (in this case it's zero because freefall)
g = acceleration due to gravity = 9.8 m/s^2
d = distance or height
We are looking for terminal velocity (the velocity of object just before it hits the ground). Substituting the values:
vf^2 - vo^2 = 2gd
vf^2 - 0 = 2 (9.8) (310)
vf^2 = 6076
vf = 77.95 m/s

hope this helps~ `u`
(I apologize if someone has already posted an answer/solution before me. I've got slow internet and I can't seem to post my comment right away.)