Answer:
The power is 
Explanation:
From the question we are told that
The distance from the siren is 
The intensity level is 
The threshold of hearing is 
Generally the intensity level is mathematically represented as
![\beta = 10dB * log [\frac{I}{I_o} ]](https://tex.z-dn.net/?f=%5Cbeta%20%20%3D%20%2010dB%20%2A%20log%20%5B%5Cfrac%7BI%7D%7BI_o%7D%20%5D)
Where I is the intensity at which the siren radiates the sound
substituting values
![49 = 10 * log [\frac{I}{1.0 *10^{-12}} ]](https://tex.z-dn.net/?f=49%20%20%3D%20%2010%20%2A%20log%20%5B%5Cfrac%7BI%7D%7B1.0%20%2A10%5E%7B-12%7D%7D%20%5D)
=> 
Now the amount of power the siren put out is mathematically evaluated as
Where A is the area of the siren which is taken as a sphere and it is mathematically evaluated as
So
substituting values
Answer:
μk = (Vf - Vc)/(T×g)
Explanation:
Given
Vi = initial velocity of the car
Vf = final velocity of the car
T = Time of application of brakes
g = acceleration due to gravity (known constant)
Let the mass of the car be Mc
Assuming only kinetic frictional force acts on the car as the driver applies the brakes,
The n from Newtown's second law of motion.
Fk = Mc×a
Fk = μk×Mc×g
a = (Vf - Vc)/T
Equating both preceding equation.
μk×Mc×g = Mc × (Vf - Vc)/T
Mc cancels out.
μk = (Vf - Vc)/(T×g)
As the ship is not in motion compared with passengers on the ship so
it will be
a lighthouse on a nearby island
so correct answer will be C
hope it helps
