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4 years ago

I'm sad bc I can't figure this out

Physics

1 answer:

Alla [95]4 years ago

5 0

The answer should be: C :)

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You are trying to overhear a juicy conversation, but from your distance of 20.0 m , it sounds like only an average whisper of 30

12345 [234]

Answer:

r₂ = 0.2 m

Explanation:

given,

distance = 20 m

sound of average whisper = 30 dB

distance moved closer = ?

new frequency = 80 dB

using formula

$\beta = 10 log(\dfrac{I_1}{I_0})$

I₀ = 10⁻¹² W/m²

now,

$30 = 10 log(\dfrac{I_1}{10^{-12}})$

$\dfrac{I_1}{10^{-12}}= 10^3$

$I_1= 10^{-8}\ W/m^2$

to hear the whisper sound = 80 dB

$80 = 10 log(\dfrac{I_2}{10^{-12}})$

$\dfrac{I_2}{10^{-12}}= 10^8$

$I_2= 10^{-4}\ W/m^2$

we know intensity of sound is inversely proportional to square of distances

$\dfrac{I_1}{I_2}=\dfrac{r_2^2}{r_1^2}$

$\dfrac{10^{-8}}{10^{-4}}=\dfrac{r_2^2}{20^2}$

$10^{-4}=\dfrac{r_2^2}{20^2}$

r₂ = 0.2 m

6 0

4 years ago

Which of the following is a physical change?

ella [17]

All of these are chemical changes except evaporation.

4 0

3 years ago

Select the statements that describe a vector. Check all that apply.

DerKrebs [107]

By definition, vectors are quantities that have magnitude (positive or negative) and direction.
Graphically, they are illustrated by directed line segments, with arrows that indicate the direction.

Evaluate the given statements.
1. Vectors have a size only. FALSE
2. Vectors have a size and a direction. TRUE
3. Vectors are indicated with arrows. TRUE
4. Vectors can have only positive values. FALSE
5. Vectors can have positive or negative values. TRUE

3 0

3 years ago

Read 2 more answers

A power transmission line is hung from metal towers with glass insulators having a resistance of 1.00×109 Ω . What current flows

Hunter-Best [27]

Answer:

The current flows through the insulator is 2 mA.

Explanation:

Given that,

Resistance $R=1.00\times10^{9}\ \Omega$