A swimmer can swim 4.00 km/h in still water. He heads south across a river that flows east at 2.00 km/h. The river is 0.500 km w
1 answer:
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The power expended is 500 W
Explanation:
First of all, we start by calculating the work done by the man in order to ascend: this is equal to the gravitational potential energy gained by the man, which is
where
m = 50 kg is the mass of the man
is the acceleration of gravity
is the change in height
Substituting,
Now we can calculate the power expended, which is given by
where
W = 2500 J is the work done
t = 5 s is the time elapsed
Substituting, we find
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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.