Real Life Examples: Resonance Frequency and Standing Waves 1. Find the first and second lowest resonance frequencies of air oscillations in between two parallel buildings separated by 23 m distance. Take 342 m/s for the speed of sound in air. The first frequency, f1 = 7.434 l Units Hz v '/ . The second frequency, f2 2' 14.868 l Units Hz v V . 2. How deep should be ocean to enhance physiologically harmful infrasonic waves of 9 Hz frequency? Take 1.5 km/s for the speed of sound in water and find the minimum and next to minimum depths of the ocean. Hint: in this case the quantization rule for standing waves is: Z + (N 1) - 5 : L , where N = 1,2,3,... an integer number. The minimum depth, h1 : Units m v '/ . The next to minimum depth, h; = Units m v '/ . 3. Why do you think the shape of stringed instruments such as violins, guitars and cellos is curved and reminds a \"hourglass\" figure? How does this shape effect the quality of sound? Please write a small paragraph below (up to 100 words)