The boy exits the stairwell at the 4th floor, which is 42 ft above the ground. How many seconds will it take him to get to the 4th floor from a height of 136 ft?

Question

asked Feb 12, 2021 227k views

1 Answer

JanT · Answer 1 · 2021-02-16T09:56:30+0000

Answer:2.41 s

Explanation:

Given

Stairwell is at a height of
$h=42\ ft$

and Height from where he starts
$H=136\ ft$

Total height boy needs to cover is

=H-h

$\Rightarrow H-h=136-42=94\ ft$

using

s=ut+(1)/(2)at^2

where
s=displacement

$u=initial\ velocity$

a=acceleration

t=time

$here\ initial\ velocity =0$

94=0+(1)/(2)(32.2)(t)^2

t^2=5.83

$t=2.41\ s$