When an object reflects all the light waves that strike it looks white or black?
1 answer:
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Answer:
B) the sound source moves towards you at 100 m/sec
Explanation:
The Dopper Effect is a phenomenon that occur when there is relative motion between an observer and a source of a wave. When this situation occurs, there is an apparent shift in frequency of the wave, as observed by the observer.
The apparent frequency observed by the observer is given by
where
f is the original frequency of the wave
f' is the apparent frequency
v is the speed of the wave
is the velocity of the observer (positive if moving towards the source of the wave, negative otherwise)
is the velocity of the source (negative if moving towards from the observer, positive otherwise)
In this problem, we want to find the scenario in which the sound frequency is higher.
We see that in all 4 scenarios, the sound source is moving: this means we have to find the scenario in which the denominator of the equation is smaller.
First of all, we notice the sound source moves towards the observer, is negative, so the denominator is higher: this means that the correct option must be either A or B.
Also, we notice that since is negative, a value larger in magnitude will mean a smaller denominator: therefore, the correct answer will be
B) the sound source moves towards you at 100 m/sec
Since this situation will make the denominator of the formula the smallest possible.
Answer:
(a) 1500 m
(b) 2827.43m
Explanation:
Given that the time for one cycle of the swing is 1 s
The radius of the swing, R= 3.0m
The angle covered, \theta, by each swing is a quarter of the circle. i.e.
Speed of running of women =5 m/s.
Time of running = 5 minutes= 5 x 60 secondes= 300 s.
(a) As distance= (speed) x (time)
So, the required distance= 5 x 300 m= 1500 m.
(b) As there are two swings in one cycle, so, the distance covered in one swing is the length of the circular shown in the figure.
As arc length, , where \theta is the angle, in radian, subtended by the arc at the center, and R is the radius of curvature of the arc.
So, the distance covered by the child in 1 swing .
In 1 cycle, there are 2 swings, so distance covered in 1 cycle .
Now, in 1 second there is 1 cycle, so in 5 minutes there will be 300 cycles.
So, the total distance covered by the child
.
