Rebecca jogs in place for two minutes before her track meet. Rebecca weighs 100 pounds. Which of the following statements is tru
2 answers:
Answer:
B. Rebecca has not done work because she has not moved a distance.
Explanation:
In physics, work represents the amount of energy necessary for a force to move a body a certain distance.
, where <em>F</em> is the force, <em>d</em> the distance and <em>W</em> the work of the force <em>F.</em>
Since Rebecca jogs in place, the distance is zero, an so does the work.
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Answer:
92.25m
Explanation:
In order to solve the exercise, it is necessary to apply the concept of construtive interference due to a path difference.
The formula is given by,
where,
n is the index of refraction of the medium in which the wave is traveling
wavelenght
is the path difference
m = integer (0,1,2,3...)
Since in this case we are dealing with an atmospheric environment, where air is predominant, we approximate n to 1.
And since we need the reflected wave,
Where x is the distance in one direction without return.
The distance must correspond to the minimum therefore m = 0, so
Then the minimum distance is:
Therefore the minimum distance from the mountain to the receiver that produces destructive interference at the receiver is 92.25m