• Jayhawk1
In summary, the conversation discusses a problem involving a tornado warning siren emitting sound waves uniformly in all directions. The intensity of the siren is given at a distance of 15 m and the task is to find the intensity at a different distance, the total power output of the siren, and the distance at which the intensity is reduced by 15 dB. The answers for parts a and b have been figured out, but there is difficulty in solving part c due to the use of logarithms and intensity ratios.
Jayhawk1
Here is the trouble problem...

11) A tornado warning siren on top of a tall pole radiates sound waves uniformly in all directions. At a distance of 15 m the sound intensity of the siren is 0.39 . Neglect any effects from reflection of the sound waves from the ground. a) At what distance from the siren is the intensity 0.19 ? b) What is the total acoustical power output of the siren? c) At what distance is the sound intensity reduced by 15 dB from its level at 15 m?

a) 21.5 m
b) 1100 Watts

Ok... so I figured out parts a and c, but I have no clue for part c- and the same seems to go for most of my class. I think the change might be very small, but I don't know how to get it. Any help would be appreciated. Thanks!

What are the dimensions of .39 and .19? Knowing that should lead you to an answer for b) I believe the customary dimensions would give you intensity in watts/meter^2. Intensity is the power per unit area, and the area in your case is the total area of the sphere centered at the source.

Sorry... I meant I didn't understand part C... any help?

The decibel scale is based on logarithms. In terms of intensity

$$L = 10log({\frac{I}{I_0}})$$

You need to find the intensity ratio that gives you L = -15 and from that determine the distance ratio and then the final distance

## 1. What is a tornado warning siren?

A tornado warning siren is a loud, outdoor alarm system designed to warn people of an approaching tornado. These sirens are typically used in areas prone to tornadoes and are activated by local authorities when a tornado has been spotted or indicated by weather radar.

## 2. How do tornado warning sirens work?

Tornado warning sirens work by emitting a loud, distinct sound that can be heard over a large area. Most sirens are activated by a central control panel or computer system, which receives alerts from meteorological agencies or trained spotters. The sound is produced by a rotating motor and horn, similar to a megaphone, and can reach decibel levels as high as 120 dB.

## 3. How effective are tornado warning sirens?

The effectiveness of tornado warning sirens can vary depending on various factors such as the distance from the siren, terrain, and weather conditions. Generally, sirens are most effective in flat, open areas and can reach a range of 1-2 miles. However, they should not be relied upon as the sole warning system, and it is crucial to have multiple ways to receive tornado warnings, such as through weather radios or mobile alerts.

## 4. Why do tornado warning sirens sound even when there is no tornado?

Tornado warning sirens are often part of a larger emergency notification system that includes other types of alerts, such as severe thunderstorm or flash flood warnings. In some cases, sirens may also be tested regularly to ensure they are functioning correctly. It is essential to familiarize yourself with the specific protocols and signals used in your area to avoid confusion.

Yes, tornado warning sirens are continuously being improved and upgraded to enhance their effectiveness and reach. New technologies, such as digital sirens and wireless activation systems, are being implemented to provide faster and more accurate warnings. Additionally, local authorities regularly review and update their siren systems to ensure they are meeting safety standards and meeting the needs of their community.

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