# physics

Factory Worker A is exposed to a sound of a constant intensity of 6.30 × 10–4 W m–2 at a distance of 1.00 m from a noisy machine. The frequency of the sound is 4.00 kHz.
(a) What is the sound level in decibels (dB) of this sound?
(b) By what factor would the amplitude of this sound wave need to change to decrease the sound level by 8 dB?

I think the first answer a) is 10log(6.3*10^-4/10^-12)=88dB but i'm unsure how to answer b

1. 👍 0
2. 👎 0
3. 👁 288
1. Since the sond level is less than the
reference(1Watt), the answer will be negative. If the sound level was 1Watt,
the answer would be 0db. If the sound
level was greater than 1 Watt, the answer would be positive.

a. 10Log(P2/P1) = 10Log(6.3*10^-4W/1W) = 10 * (-3.2) = -32db.

b. -32db - 8db = -40db = The new power
ratio in decibels.

10Log(P2/1W) = -40db,
Divide both sides by 10:
Log(P2/1) = -4.0,
P2/1 = 10^-4,
P2 = 10^-4 Watts = The new power.

6.3*10^-4W / 10^-4W = 6.3 = Factor
by which the power was decreased.

Since the power is proportional to the
square of the voltage,the voltage will be reduced by a factor of:
sqrt(6.3) = 2.51.

1. 👍 0
2. 👎 0

## Similar Questions

1. ### algebra 2

the loudness L of a sound in decibels is given L=10log10R, where R is the sound's relative intensity. if the intensity of a certain sound is tripled, by how many decibels does the sound increase? due tomorrow, tuesday, april 5th,

asked by math challenged on April 4, 2011
2. ### algebra 2

THe loudness L of a sound is measured by L=10 log10^R where R is the sound's relative intensity. One person talks with a relative intensity of 10^6 or 60 decibels. How much louder would 100 people be ,talking with the same

asked by lexi on April 19, 2017
3. ### Physics

I need help on this question: You are given information on the intensity level (which is a measure of the sound intensity) at a point and its distance from the sound source. To make use of this information, you will need to

asked by J1 on July 14, 2020
4. ### physics

The intensity of a certain sound wave is 6 ì W.cm2. if its intensity is raised by 20 decibels, the new intensity (in ìW/cm2) is : a. 60 b. 6.6 c. 6.06 d. 600 E. 12

asked by khaled fayek on July 24, 2015
5. ### History

Imagine you are one of the factory workers at Lowell Mills tasked with creating the headline story for this month’s factory newspaper. Factory Workers—Factory Worker Template 1. First paragraph: Hook your reader into wanting

asked by Anonymous on March 11, 2013
1. ### physics

A rocket in a fireworks display explodes high in the air. The sound spreads out uniformly in all directions. The intensity of the sound is 1.90 10-6 W/m2 at a distance of 120 m from the explosion. Find the distance from the source

asked by Anonymous on December 3, 2011
2. ### Physics

The intensity due to a number of indipendent sound sources is the sum of the individual intensities. A) When four quadruplets cry simultaneously, how many decibels greater is the sound intensity level than when a single one cries?

asked by Amanda on March 29, 2008

Hello! Can someone please help me out for this question? The loudness, L, of a sound in decibels can be calculated using the formula L= 10 log(I/ F) where I is the intensity of the sound in watts per square metre and F= 10^ -12 .

asked by Joan on January 19, 2010
4. ### Physics

A fan at a rock concert is 45.0 m from the stage, and at this point the sound intensity level is 108 dB. Sound is detected when a sound wave causes the tympanic membrane (the eardrum) to vibrate . Typically, the diameter of this

asked by Kyle on May 4, 2012
5. ### M361

A factory worker productivity is normally distributed. worker A produces an average of 84 units per day with a standard deviation of 24. worker B produces at an average rate of 74 units per day with stanard deviation of 25. (a)

asked by mercy on April 7, 2013