To develop this problem it is necessary to apply the concepts related to Sound Intensity.
By definition the intensity is given by the equation
Where,
I = Intensity of Sound
= Intensity of Reference
At this case we have that 15 engines produces 15 times the reference intensity, that is
And the total mutual intensity is 100 dB, so we should
Therefore each one of these engines produce D. 88dB.
Answer:
The value of g = 0.6168 m/s².
Explanation:
Given that,
On a planet X,
Length of the pendulum(L) = 0.25 meters,
Time period of the pendulum(T) = 4 seconds.
We have to find the 'g' value on the planet.
The 'g' value on a planet can be found by a pendulum with help of the formula,
T = 2π ×
From this, g = 4π² ×
Using the above formula and substituting the values,we get,
g = 0.6168 m/s².
Complete Question
A commuter train passes a passenger platform at a constant speed of 39.6 m/s. The train horn is sounded at its characteristic frequency of 350 Hz.
(a)
What overall change in frequency is detected by a person on the platform as the train moves from approaching to receding
(b) What wavelength is detected by a person on the platform as the train approaches?
Answer:
a
b
Explanation:
From the question we are told that
The speed of the train is
The frequency of the train horn is
Generally the speed of sound has a constant values of
Now according to dopplers equation when the train(source) approaches a person on the platform(observe) then the frequency on the sound observed by the observer can be mathematically represented as
substituting values
Now according to dopplers equation when the train(source) moves away from the person on the platform(observe) then the frequency on the sound observed by the observer can be mathematically represented as
substituting values
The overall change in frequency is detected by a person on the platform as the train moves from approaching to receding is mathematically evaluated as
Generally the wavelength detected by the person as the train approaches is mathematically represented as