Answer:
(a) Approximately 968 Hz.
Explanation:
The observed frequency is less than 1003 Hz because of Doppler's Effect. When the source is moving away from an observer that doesn't move, the equation for the observed frequency would be:
,
where in the context of this problem,
- is the speed of sound in the air.
- is the speed at which the source moves away from the observer.
- is the frequency at the source.
Apply this equation to find :
.
Here's an alternative explanation.
The frequency of the siren at the source is . That corresponds to a period of .
In other words, at the source, a peak arrives about every .
The source is moving away from the observer at a speed of . In the between the first and the second peak, the source moved away from the observer. It would take an extra for the sound to cover that extra distance.
As a result, the period of the sound would appear to be to the observer.
That corresponds to an observed frequency of . (Same as the answer from the formula.)
Answer:
400N
Explanation:
Newton's second law of motion
F = ma
20 x 20 = F
F = 400
Answer:
The answer would be D
Explanation:
It's quite simple, the Universal Law of Gravitation states that all mass no matter the size, shape, or weight acts equally upon the force of gravity of the gravitational object. Basically, between all sizes, shapes, weights of masses, gravity applies the same gravitational force with all. Gravity with friction would be something else, which is also states in the Theory of Gravitation.