Two loudspeakers in a plane are 2.0 m apart and in phase with each other. Both emit 700 Hz sound waves into a room where the speed of sound is 341 m/s. A listener stands 5.0 m in front of the loudspeakers and 2.0 m to one side of the center line. Is the interference at this point completely constructive, completely destructive, or in between

interference is between destructive  and constructive

Explanation:

The interference of two sound waves periodicity in phase by the speakers is

          Δr =

in this case they indicate that the frequency is f = 700 Hz, the wave speed is

            v =λ f

            λ = v / f

            λ = 341/700

            λ = 0.487 m

Let's use the Pythagorean theorem to find the distance that each wave travels

        r₁ =

let's measure the distance from speaker 1

          r₁ =

          r₁ = 5,099 m

the distance from the second speaker

          r₂ = \sqrt{x^2 + y^2}

          r₂ =

          r₂= 5.831 m

the difference in the way is

          Δr = r₂ -r₁

          Δr = 5,831 - 5,099

          Δr = 0.732 m

          = Δr /λ

         \frac{ \phi }{2\pi } = 0.732 / 0.487

         \frac{ \phi }{2\pi } = 1.50

this is the phase difference this phase difference is approximately

            Ф= =1.57,

so the interference is between destructive ( Ф = π) and constructive (Ф=2π)

answer: the exterior temperature of commercial jet planes as they leave the stratosphere and return to the ground increases steadily.

explanation:

the lower most layer of atmosphere is troposphere which extends from 0 to 12 km above the surface of the earth. the temperature initially decreases as distance is increased from the earth's surface. commercial jets fly in lower part of the stratosphere. the stratosphere extends upto 50 km. the temperature in stratosphere starts rising again due to presence of ozone which traps the uv rays.

thus, when the planes leave the stratosphere and return to the ground, the exterior temperature increases steadily.