Question

your drop a coin from the top of a hundred-story building(1000m). If you ignore air resistance, how fast will it be falling right before it hits the ground?How long does it take to hit the ground?

Answer 1

h=1/2*g*t²,
so t=√(2h/g)= 10√2 s

v=gt=100√2 m/s

Answer 2

consider the motion of con from top to bottom

Y = vertical displacement = 1000 m

a = acceleration due to gravity = 9.8 m/s²

v₀ = initial velocity at the top = 0 m/s

v = final velocity at the bottom = ?

using the kinematics equation

v² = v²₀ + 2 aY

v² = 0² + 2 (9.8) (1000)

v = 140 m/s

t = time taken to hit the ground

Using the equation

v = v₀ + at

140 = 0 + 9.8 t

t = 14.3 sec