Beats.
When two sound waves of different frequency approach your ear, the alternating constructive and destructive interference causes the sound to be alternatively soft and loud - a phenomenon which is called "beating" or producing beats. The beat frequency is equal to the absolute value of the difference in frequency of the two waves.
Answer:
C. 590 mph

Explanation:
Given:
- velocity of jet,

- direction of velocity of jet, east relative to the ground
- velocity of Cessna,

- direction of velocity of Cessna, 60° north of west
Taking the x-axis alignment towards east and hence we have the velocity vector of the jet as reference.
Refer the attached schematic.
So,

&


Now the vector of relative velocity of Cessna with respect to jet:



Now the magnitude of this velocity:

is the relative velocity of Cessna with respect to the jet.
Answer:
191433.4 hours
Explanation:
We are given that In the average US household, the television is on 6.75 hours/day! How many hours will have passed after 77.7 years (the average lifeexpectancy of an American)?
1 year - 365 days
Given that the television is on 6.75 hours/day.
If 1 year = 365 days
Convert 77.7 years to days by multiplying it by 365
77.7 × 365 = 28360.5 days
So the number of hours will be:
28360.5 × 6.75 = 191433.375 hours
Therefore, 191433.4 hours will pass.
Non of the options is correct.
Never is the correct answer