An object is thrown vertically from a height of #2 m# at #4 m/s#. How long will it take for the object to hit the ground?

1 Answer
Apr 17, 2017

Answer:

1.4 Sec

Explanation:

We know when it attains maximum height it Final velocity will be zero .
so ,
from eq. #v=u+a*t#

time taken to attain maximum height is =#(-u)/a#(for this case)
which is =#(-4)/-10=0.4 sec# #"------------(1)"#

now distance traveled upward #=>#
#S=ut+1/2at^2##"--------(2)"#

we get
#S=4*0.4+1/2*(-10)*(0.4)^2=0.8 m#

now it again falls from that height to ground which is #2.0+0.8=2.8m#

now time taken to hit the ground is taken by eq 2#=>#
#2.8=1/2*10*t^2=0.74 sec#

so we will add (1) and (2) to get our answer we get=#0.4+0.74=1.4sec#