1. REPORTERS: David Ecoben Shanina Jamero Kinah Colita Ritchel Bagayas

2. 1. What is Wave? 2-5. Draw and Label the parts of wave. 6. A guitar string with a length of 80.0 cm is plucked. The speed of a wave in the string is 400 m/sec. Calculate the frequency of the first, second, and third harmonics. 7. A pitch of Middle D (first harmonic = 294 Hz) is sounded out by a vibrating guitar string. The length of the string is 70.0 cm. Calculate the speed of the standing wave in the guitar string. QUESTIONS

3. 8-9. Sound waves consist of _____________ and ______________. 10. It is the interdisciplinary science that deals with the study of all mechanical waves in gases, liquids, and solids including vibration, sound, ultrasound and infrasound. 11. Give the formula of Intensity and Loudness 12. True or False : The speed of the sound is directly proportional to its temperature 13. It is the change in frequency of a wave for an observer moving relative to its source 14-15. Give a situation in which Doppler effect may occur. QUESTIONS

5. ANSWERS 1. Answers may vary 2-5.

6. 6. Answers: f 1 = 250 Hz; f 2 = 500 Hz; f 3 = 750 Hz Given: L = 0.80 mv = 400 m/s Let = wavelength = 2 L = 2 (0.80 m) = 1.6 m Now rearrange the wave equation f 1 = v /2L= (400 m/s) / (1.6 m) = 250 Hz The frequencies of the various harmonics are whole-number multiples of the frequency of the first harmonic. Each harmonic frequency (f n ) is given by the equation f n = n f 1 where n is the harmonic number and f 1 is the frequency of the first harmonic. ANSWERS

7. 7. Answer: v = 412 m/s Given: L = 0.70 mf = 294 Hz (1st) The strategy for solving for the speed of sound will involve using the wave equation v = f where is the wavelength of the wave. The frequency is stated but the wavelength must be calculated from the given value of the length of the string. For the first harmonic, the wavelength is twice the length of the string. = 2 L = 2 (0.70 m) = 1.4 m Now substitute into the wave equation to solve for the speed of the wave. v = f = (294 Hz) (1.4 m) v = 412 m/s ANSWERS

8. 8-9. Rarefactions and Compressions 10. Acoustics 11. β (in dB)= 10 log( I / Io ) 12. True 13. Doppler Effect 14-15. Answers may vary ANSWERS