Question

A stone is dropped from the edge of a roof, and hits the ground with a velocity of -180 feet per second. How high (in feet) is the roof? Note: the acceleration of an object due to earth's gravity is 32 f t sec 2

Answer 1

Answer:

d = 506.25 ft

Explanation:

As we know by kinematics that

$v_f^2 - v_i^2 = 2 a d$

here we know that initially the stone is dropped from rest from the edge of the roof

so here initial speed will be zero

now we have

$v_i = 0$

also the acceleration of the stone is due to gravity which is given as

$g = 32 ft/s^2$

now we have

$v_f = 180 ft/s$

so from above equation

$180^2 - 0 = 2(32)d$

$d = 506.25 ft$