1. Physics 101 MFA Chapter 16, Problem 1 Suppose you are standing a distance D away from a speaker that is radiating sound in a spherically uniform way. You walk away from the speaker until the loudness of the sound is reduced by a factor of two. About how far from the speaker are you now (neglecting any reflections from the ground)? 1. 10D 2. 4D 3. 3D 4. 2D correct

2. Physics 101 MFA Speaker radiating power P I 1 = P/(4  D 1 2 ) D1D1 I 2 = P/(4  D 2 2 ) D2D2 Changing I by 10 will change loudness by 2 We want I 1 /I 2 = 10

3. Physics 101 MFA Chapter 16, Problem 2 A: You are driving along the highway at 65 mph, and behind you a police car, also traveling at 65 mph, has its siren turned on. B: You and the police car have both pulled over to the side of the road, but the siren is still turned on. In which case does the frequency of the siren seem higher to you? 1. Case A 2. Case B 3. same vsvs f vovo f’ v correct