Physics, 26.11.2019 05:31 winterblanco

A60 year old person has a threshold of hearing of 95.0 db for a sound with frequency f=10,000 hz. by what factor must the intensity of a sound wave of that frequency, audible to a typical young adult, (sound level=43.0 db) be increased so that it is heard by the older person.

if you know the sound level in db, then you can compute the sound intensity and take the ratio.

hint*
in the problem, they gave the intensity as decibels but want to know by what factor to increase the intensity (i) for the young person to get a sound that the older person can hear.

ignore f completely.

decibels (db) need to be converted to i using this equation:
i=(10^(db/10))*10^-12
do this for each db and divide the older person's db by the younger's.

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Answer from: princessbreanna0

The intensity increased by a factor of 158489

Explanation:

Given that,

Sound level = 95.0 dB

Sound level = 43.0 dB

Frequency = 10000 Hz

We need to calculate the ratio of sound intensity

Using formula of sound level

$sound\ level =10 log\dfrac{I}{I_{0}}$

Put the value into the formula

$95.0=10\ log\dfrac{I_{1}}{I_{0}}$ ...(I)

$43.0=10\ log\dfrac{I_{2}}{I_{0}}$ .....(II)

Subtracting these equations

$52.0=10\ log\dfrac{I_{1}}{I_{2}}$

$\log\dfrac{I_{1}}{I_{2}}=5.2$

Taking inverse log

$\dfrac{I_{1}}{I_{2}}=10^{5.2}$

$\dfrac{I_{1}}{I_{2}}=158489$

Hence, The intensity increased by a factor of 158489

Answer from: Quest

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

$f\alpha \frac{dp}{dt}$

⇒ $f= k \frac{dp}{dt}$

here k is the proportionality constant whose value is 1.

$f=\frac{dp}{dt}$

$f= \frac{d[mv]}{dt}$

$f= m\frac{dv}{dt} +v\frac{dm}{dt}$

$f=ma+v\frac{dm}{dt}$ [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.

Answer from: Quest

in order to follow the instructions and complete the statements, i need to use data from table c of your student guide. can you think of a way to let me see your student guide for a while ? i can't answer the question without the data in table c.

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