Answer:
he maximum frequency occurs when the denominator is minimum
f’= f₀ 
Explanation:
This is a doppler effect exercise, where the sound source is moving
f = fo 
when the source moves towards the observer
f ’=f_o 
Alexandrian source of the observer
the maximum frequency occurs when the denominator is minimum, for both it is the point of maximum approach of the two objects
f’= f₀
Thermos bottles are equipped with the parts that can prevent the hot water from cooling down by the three ways: Supporting the inner container by a few heat-insulating supporters to minimize the heat loss through heat conduction, using a vacuum space between the outer and the inner vessels to eliminate the heat loss by the air convection, and giving a high reflectivity to the inner surface of the outer vessel and the whole surface of the inner container to reduce the heat loss due to the radiation cooling.
To increase it's size
Waxing is the opposite of waning, which is to decrease.
Atomic Motion definition: Atomic motion is the continual movement of atoms and molecules that are contained within everything in the universe.
C. A mechanical wave generally travels faster in gases than liquids.
