Question

A coin was dropped from the top of a hundred story building (1000m).Ignoring 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

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