Answer:
The positive displacement from the midpoint of its motion at the speed equal one half of its maximum speed is 3.56 cm.
Explanation:
Maximum speed is :
v (max) = Aω
Speed v at any displacement y is given by
=
(
-
) ........................................................ i
And,
v =
v (max)
or, 2 × v = Aω .................................................... ii
Eliminating ω from equations i and ii,
=
(
-
)
or,
= (
)
=(
) 
or, y = 3.56 cm.
First we gotta use an equation of motion:

Our vertical distance d= 100 m, initial vertical speed u = 0 m/s (because velocity is fully horizontal), and vertical acceleration a = 9.8 m/s2 because of gravity. Let's plug it all in!

Now we just need to solve for t:

Hit the calculators, and you'll get 4.5 seconds!
Answer:
v= 449.8 m/s
Explanation:
Given data
Frequency= 346Hz
Wave length= 1.4m
The expression below is used to find the speed

substitute

Hence the speed is v= 449.8 m/s
because they are floating on top of the liquid mantle.
Given that amplitude and energy are related, the amplitude of a wave is dependent upon A. the amount of energy carried by the wave.
These two are connected, so one affects the other and vice versa.