Two loudspeakers 42.0 m apart and facing each other emit identical 115 Hz sinusoidal sound waves in a room where the sound speed is 345 m/s. Susan is walking along a line between the speakers. As she walks, she finds herself moving through loud and quiet spots. ?

She passes through a loud spot at x = 19.5m from the first speaker. Constructive interference occurs here.

At the quiet spot destructive interference occurs. The minimum distance for this to occur is 20.25 from the first speaker.

Explanation:

i think it’s a. this is because if they measured the mass of something with a mass of 150g, then their final answer would have to be approximately 150g. though all of their answers are almost 150, rosa and tran have the closest answers (or the exact answer) to the accurate one.

no. dot product   =0 when vecs at right angles