Asiren produces a 12,300 hz frequency and an intensity of 2.8x10^-6 w/m^2 at a distance of 10 m. what is the speed of the sound produced by the siren in the at a temp of 25°c?
what is the intensity level in db, at a distance of 10 m from the source?
what would be the intensity and the intensity level at a distance of 1x10^2 m from the siren?
what would be the observed frequency of the siren if the source was approaching the observer at a speed of 40 m/s?

You are given a vector a = 125i and an unknown vector b that is perpendicular to a. the cross-product of these two vectors is a × b = 98k. what is the y-component of vector b?

Explain the comparisons between nature and packingtown that appears on pages 81 and 82 answer

As you are trying to move a heavy box of mass m, you realize that it is too heavy for you to lift by yourself. there is no one around to , so you attach an ideal pulley to the box and a massless rope to the ceiling, which you wrap around the pulley. you pull up on the rope to lift the box. use g for the magnitude of the acceleration due to gravity and neglect friction forces. once you have pulled hard enough to start the box moving upward, what is the magnitude f of the upward force you must apply to the rope to start raising the box with constant velocity? express the magnitude of the force in terms of m, the mass of the box.