speed of slower=x; distance in 6 hours is 6x
speed of larger=2x; distance in 6 hours is 12x
12x-6x=204 miles
 6x=204
x=34 mph slower, 204 miles in 6 hours.
2x=68 mph, faster, 408 miles in 6 hours, and difference is 204 miles

6 0

3 years ago

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By what factor must the amplitude of a sound wave be increased in order to increase the intensity by a factor of 9?a. 9 b. 2 c.

Marta_Voda [28]

Answer:

option D

Explanation:

given,

$intensity\ \alpha \ (Amplitude)^2$

increase the intensity by factor of 9

I₁ = I₀

I₂ = 9 I₀

now,

$\dfrac{I_1}{I_2}=\dfrac{A_1^2}{A_2^2}$

$\dfrac{I_0}{9I_0}=(\dfrac{A_1}{A_2})^2$

$(\dfrac{A_1}{A_2})^2=\dfrac{1}{9}$

$\dfrac{A_1}{A_2}=\dfrac{1}{3}$

A₂ = 3 A₁

hence, amplitude increase with the factor of 3

so, the correct answer is option D

4 0

2 years ago

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