Solution-
Height h = 0.680m
So the displacement of the Fluffy S = 0.68 m
Accleration a = -g
                     =
-9.8 m / s ^ 2
Iinitial speed of the Fluffy u = ?
final speed i.e., speed at maximum height  is v = 0 m /
s
from the relation v ^ 2 - u ^ 2 = 2aS
                                  -
u ^ 2 = 2 ( -g ) S
                                           u=
√[ 2 gS ]
                                            =
3.65 m / s
(b). time the flea in air = time of scent + time ofdecent
                                  =
( u / g ) + ( u / g )
                                  =
2u / g
=2*3.65/9.81
                                  =
0.744 s
