Two speakers are 3.0 m apart and play identical tones of frequency 170 Hz. Sam stands directly in front of one speaker at a distance of 4.0 m. Is this a loud spot or a quiet spot? Assume that the speed of sound in air is 340 m/s.

he phase difference is π the destructive interference and the lujar is a still or silent place

Explanation:

This is a sound interference exercise where the amino difference is equal to the phase difference of the sound.

      Δr / λ = ΔФ / 2π

Let's find the path difference

     r₁ = 4m

     r₂ = √ (4² + 3²) = 5 m

     Δr = r₂ - r₁

     Δr = 5-4 = 1m

Let's find the wavelength of the sound

        v =  λ f

         λ = v / f

         λ = 340/170

         λ = 2m

Let's find the phase difference between the two waves

      ΔФ = Δr 2π / λ

      ΔФ = 1 2π / 2

      ΔФ = π

Since the phase difference is π the destructive interference and the lujar is a still or silent place

acceleration = (change in speed) / (time for the change)

change in speed = (20-120)= -100 m/s.

1.5 min = 90 sec

acceleration = -100/90 = -1.11 m/s^2.

we don't care about the 150kg or the 2,500 meters. they don't make any difference.

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