Answer:

Explanation:
= Initial diameter = 4 cm
= Initial velocity = 1 m/s
= Final diameter = 7.8 m
= Final velocity
= Area = 
From the continuity equation we get

The speed of water at the second floor is
.
The energy of a photon is given by

where h is the Planck constant and f is the photon frequency.
We can find the photon's frequency by using the following relationship:

where c is the speed of light and

is the photon's wavelength. By plugging numbers into the equation, we find

And so now we can find the photon energy

We know that 1 Joule corresponds to

So we can convert the photon's energy into electronvolts:
Yes, because cell phones use scientific structure to build.