A hammer is dropped from the roof of a building 1000 meters tall. How long will it

take to hit the ground?

Let's use the kinematic equation

s = ut + ½at²

Where

s = distance fallen

u = initial velocity

t = time taken

a = acceleration

Here the hammer is dropped so a = g = gravitational acceleration

u = 0 because the hammer is dropped.

So by substituting you get,

1000 = 0 + ½*10*t²

t² = 200

t = 14.14 s