This speaker is part of Rice's Orwellian public announcement system. Assume it emits a spherical wave at 300 Hz that travel at 343 m/s. Your head is 51.20 m from the speaker. Your friend is walking behind you and his head is 51.835 m from the speaker. What is the difference in phase between the sound waves that you hear and your friends hear in degrees

Two steel balls, each of mass m, are welded to a light rod of length l and negligible mass and are initially at rest on a smooth horizontal surface. a horizontal force of magnitude f is suddenly applied to the rod as shown. determine (a) the instantaneous acceleration a of the mass center g and (b) the corresponding rate at which the angular velocity of the assembly about g is changing with time.