Answer:
Option C, increases and decreases
Explanation:
When an object making noise approaches you, the wave frequency increases leading to a higher pitch. Conversely, when it moves away from you or retreats, the wave frequency decreases leading to a lower pitch. This can be observed in ambulance sirens.
Answer:
When the ejected air is moving in the downward direction then the thrust force acts in the upward direction, due to reversal thrust, the jets can take off vertically without needing a runway this way.
Explanation:
Newton’s third law motion states that for every action there will be an equal and opposite reaction.
Thrust reversal is also known as reverse thrust. It acts opposite to the motion of the aircraft by providing the deceleration.
Commercial aircraft moves the ejected air in the forward direction means that the thrust will acts opposite to the motion of the aircraft that is backward direction due to thrust reversal. This thrust force might be used to decelerate the craft.
Uses of thrust reversal in practice:
When the ejected air is moving forward direction then the thrust force moving backward direction due to reversal thrust the speed of the craft slows down.
When the ejected air is moving in the downward direction then the thrust force acts in the upward direction, due to reversal thrust, the jets can take off vertically without needing a runway this way.
Answer:
That the universe (the balloon for this case) is expanding and that is the reason why the galaxies (the dots) appear to move away one from another.
Explanation:
By means of looking at the spectra of galaxies, it can confirm that they are moving away in an accelerated motion.
Spectral lines will be shifted to the blue part of the spectrum if the source of the observed light is moving toward the observer, or to the red part of the spectrum when it is moving away from the observer (that is known as the Doppler effect). The source in this particular case is represented for each of the galaxies.
Hence, the redshift represents this shift of the spectral lines to red part in the spectrum of a galaxy or any object which is moving away. That is a direct confirmation of how the universe is in an expanding accelerated motion.
The redshift can be define in analitic way by trought the doppler velocity:
(1)
Where 
is the wavelength shift, 
is the wavelength at rest, v is the velocity of the source and c is the speed of light.
(2)
Where z is the redshift.
The ballon example, once that it is inflating, represents how is the universe which it is expanding and that is the reason why the galaxies (the dots) appear to move away one from another.
HCIO4 is a stronger acid than HCIO because as the number of oxygen increases the oxidation number in the central atom increases which weakens the O-H bond strength and increases the acidity.
