Express nal answers in the correct SI units unless stated ulltertll'ite- crrure or highlight your nal answer. You must show affyour wort to receive any credit. it Two boys are whispering in the library. The radiated sound power from one boy's mouth is 1.6 x 10-9 W; and it spreads out uniformly in all directions with no reections. What is the minimum distance the boys must be away from the librarian so that she will not be able to hear them? The threshold of healing for the librarian is 1.00 x 10'12me2. {5 pts) 2. Two motorcycles are traveling in opposite directions at the same speed when one ofthe cyclists blasts his horn. which has frequency of 54-1 Hz. The other cyclist hears the frequency as 522 Hz. If the speed of sound in air is 344 mis, what is the speed of the motorcycles? [5 pts) 3' A some mirror in an amusement park has a radius of curvature of4_l} m. A child stands in front of the minor so that she appears 3.0 times taller than her actual height. If the image is upright, how far is she standing from the minor? {5 pts} 4. A ray of light is normally incident on face ab ofa plastic prism with an index of refraction n = 1.20 as shown. Determine the largest value of the angle a so that the ray is totally reected at the face as ifthe prism is immersed in air. [5 pts) toeidentray