Answer:
The car must be moving away from the person.
Explanation:
From Doppler's Effect, we know that when a sound source moves towards a stationary observer, the apparent frequency of that sound increases. While the apparent frequency decreases if the source moves away from the stationary observer.
The audible range of frequencies for a human ear is 20 Hz to 20000 Hz. Therefore, in order for the sound of a loud speaker to be audible for the person, the frequency must decrease below 20000 Hz.
<u>Due to this reason, the car must be moving away from the person.</u>
(a) The gas of interstellar medium can be detected from the radiations of photons of wavelength 21 cm.
(b) The gas of interstellar medium can be detected from the absorption lines present in the light from distant stars, which must be caused by a medium of density and temperature other than that of the stars emitting the lights.
<h3>
What is interstellar medium?</h3>
Interstellar medium is the matter and radiation that exist in the space between the star systems in a galaxy.
<h3>Evidence that interstellar medium contains both gas and dust</h3>
- The gas of interstellar medium can be detected from the radiations of photons of wavelength 21 cm.
- The gas of interstellar medium can be detected from the absorption lines present in the light from distant stars, which must be caused by a medium of density and temperature other than that of the stars emitting the lights.
Learn more about interstellar medium here: brainly.com/question/4173326
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A substance with LOW pH. The lower the pH, the higher the acidity level is. pH has a direct effect on how acidic a substance is. For an example, battery acid. Battery acid has a pH level of about 1. This means that battery acid is very acidic. A substance is concidered acidic when it dips below the neutral pH level of 7.
Answer:
Zero
Explanation:
Given the equation of an ellipse:
The eccentrity of an ellipse is given by:
For a circle, we have
Therefore the eccentricity of a circle is
The FIRST statement on the list is the definition of momentum, so that's the one that must be true.
