Answer:
The speed is 
Explanation:
Electric field magnitude (E) and electric force magnitude (F) are related by the equation

with q the charge of the proton (
). Because between parallel plates electric field is almost constant, electric force is constant too:

because electric force is constant, then by Newton's second law acceleration (a) is constant too, it is:

with m the mass of the proton (
):

Now with this constant acceleration we can use the kinematic equation

with v the final speed,
the initial velocity that is zero (because proton starts at rest) and d is the distance between the plates, so:

Answer:
d=510.2m
t=10.2s
Explanation:
The formulas for accelerated motion are:

From them we can get
.
We have:

And substitute:

We multiply both sides by 2a, and continue:

Being d the displacement
, we have 
For our exercise, we will write this as:

And taking upwards direction positive and imposing final velocity 0m/s (for maximum height), we have:

For the time we use:

I think the correct answer would be one half the wavelength. Waves would "feel bottom" when the water is at the depth of 0.5 of the wavelength. "Feel bottom" is a term used to describe that the depth of water affects the wave properties. Hope this answers the question.
(198,000 joule / 15 minute) x (minute / 60 sec) = 220 joule/sec = <em>220 watts
</em>