Question #35de3

1 Answer
Sep 26, 2016

Answer:

#2.71s#, rounded to two decimal places.

Explanation:

Free fall under gravity is governed by the kinematic equation
#h=ut+1/2g t^2#
Where #h# is height from which body starts falling,
#u# is its initial velocity
#g# is acceleration due to gravity and is #9.81ms^-2#
and #t# is the time taken for the fall to reach ground level.

In this question we take ground level as the sea level. Inserting given quantities we get
#36=0xxt+1/2xx9.81xx t^2#
#=>1/2xx9.81xx t^2=36#
#=> t^2=(36xx2)/9.81#
#=> t=sqrt((36xx2)/9.81)#
#=>t=+-2.71#, rounded to two decimal places.
ignoring the #-ve# root as time can not be negative
#t=2.71s#