The mechanical energy in the falling water is used to spin the generator, and gets transformed into electrical energy. That's the first choice on the list.
Answer:
Light of a shorter wavelength should be used.
Explanation:
This is studied in the phenomenon called photoelectric effect, in which light is able to release electrons from a metal, said electrons are called photoelectrons .
The experiments that have been carried out show that <u>increasing or decreasing the intensity of the light will not cause the photoelectrons to be emitted</u>, what will cause the photoelectrons to be emitted is to increase the frequency of the incident light.
And a higher frequency corresponds to a shorter wavelength according to the equation:

(where
is frequency,
the speed of light, and
the wavelength)
So the answer is that the wavelength of the light must be shortened to cause the emission of electrones.
Answer:
69.42 m
Explanation:
From the question given above, the following data were obtained:
Initial velocity (vᵢ ) = 4.9 m/s
Acceleration (a) = 4.2 m/s²
Time (t) = 4.7 s
Displacement (Δx) =?
Thus, we can obtain the displacement by using the following formula:
Δx = vᵢt + ½at²
Δx = (4.9 × 4.7) + (½ × 4.2 × 4.7²)
Δx = 23.03 + (2.1 × 22.09)
Δx = 23.03 + 46.389
Δx = 69.419 ≈ 69.42 m
Thus, the distance travelled is 69.42 m