Answer:
<em> The intensity would be 0.01432 W/</em>
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Explanation:
The sound intensity is the power that is transmitted by a sound wave per unit area.
Given that
Power output P of the 75-piece orchestra = 72.0 W
The listener's distance r = 20.0 m
The intensity of sound waves (I) can be obtained with the expression below;
I = P/A .............. 1
where P is the power
A is the area, in this case, at the distance r the sound is radiated through a sphere.
A = area of a sphere = 4π
putting it into equation 1, the intensity would be;
I = P/ 4π
Substituting our values we have;
I = 72.0 W / 4 π 
I = 0.01432 W/
Therefore the intensity would be 0.01432 W/
Use the formula for kinetic energy.
KE=1/2mv^2
KE=1/2*(82kg)*(2.8m/s)^2
KE=321.4 J
The answer is C
Answer: A = 0.02 m²
Explanation: Solution:
Pressure is expressed in the formula:
P = F / A where F = mg
= mg /A
= 50 kg ( 9.8 m/s²) / 25000 Pa
= 0.02 m²
The correct one is gamma rays. Lets go over them one by one.
Gamma rays are rays that arise from gamma decay, a type of radioactive decay. Often, after another decay, the nucleus is still unstable and it gives off energy in the form of gamma rays to stabilize itself. Hence, gamma rays have nothing to do with the electron structure, only with the nucleus of the atom.
X-rays are the product of accelerating electrons, hence only specific atoms can emit a specific energy of X-rays; similarly for the photoelectric phenomenon, the energy which is needed for photoelectrons to be created depends on the electron structure of the atom (in both cases, it is important to see how strong the bond between electron and atom is).
Finally, spectral lines differ depending on the electron structure of the atoms since electrons with different energies absorb different frequencies of light.
