Answer:
Explanation: O B. Diffraction
The speed of the rock at 20 m is 34.3 m/s
Explanation:
We can solve this problem by using the law of conservation of energy: the mechanical energy of the rock, sum of its potential energy + its kinetic energy) must be conserved in absence of air resistance. So we can write:
where
:
is the initial potential energy
is the initial kinetic energy
is the final potential energy
is the final kinetic energy
The equation can also be rewritten as follows:
where:
m = 100 kg is the mass of the rock
is the acceleration of gravity
is the initial height
u = 0 is the initial speed (the rock starts at rest)
is the final height of the rock
v is the final speed when h = 20 m
And solving for v, we find:

Learn more about kinetic energy and potential energy here:
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Answer:
Nuclear medicine or PET scanning (Positron Emission Tomography)
Explanation:
Not super sure what your question is looking for but I think it can be either. PET is a technology used in the nuclear medicine field, and nuclear medicine is a broad field of using the technology the question described.
A “real” image occurs when light rays actually intersect at the image, and become inverted, or turned upside down. ... In flat, or plane mirrors, the image is a virtual image, and is the same distance behind the mirror as the object is in front of the mirror. The image is also the same size as the object.
Since the frequency of sound in a medium is constant, therefore, the concert-goers would hear the low notes and high notes at the same time.
<h3>What is a dispersive medium?</h3>
A dispersive medium is a medium which spreads out or disperses a substance passing through it.
Since CO2 is a dispersive medium, it means sound waves passing through it would be dispersed based on wavelength.
The note of a sound depends on its frequency, the higher the frequency, the higher the note.
Frequency of sound is constant, therefore, the concert-goers would hear the low notes and high notes at the same time.
Learn more about dispersion of sound at: brainly.com/question/781734