Practice 13 Solutions

# Practice 13 Solutions - practice 13 – GADHIA, TEJAS –...

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Unformatted text preview: practice 13 – GADHIA, TEJAS – Due: Apr 19 2007, 4:00 pm 1 Question 1 part 1 of 1 10 points Two sound waves of the same frequency can interfere, but to create beats, two sound waves have to have different frequencies. Why? 1. Two waves of different frequencies inter- fere constructively, independent of on their phase difference. 2. Waves of the same frequency interfere constructively, independent of on their rela- tive phase. 3. Waves of the same frequency interfere destructively, independing on their relative phase. 4. To alternate between constructive and destructive interfrence requires different fre- quencies. correct 5. Two waves of different frequencies inter- fere destructively, independent of their phase difference. Explanation: Waves of the same frequency can inter- fere destructively or constructively, depend- ing on their relative phase, but to alternate between constructive and destructive inter- ference, two waves have to have different fre- quencies. Beats arise from such alternation between constructive and destructive inter- ference. Question 2 part 1 of 1 10 points Walking beside you, your friend takes 50 strides per minute while you take 34 strides per minute. If you start in step, when will you be in step again? Correct answer: 3 . 75 s (tolerance ± 1 %). Explanation: The “beat frequency” is 16 per minute, so you and your friend will be in step after 3 . 75 s : t = 1 f = 1 2 / min · 60 s 1 min = 3 . 75 s . Question 3 part 1 of 1 10 points You are given two waves, a transverse wave that moves to the right f 1 ( x ) and a transverse wave that moves to the left f 2 ( x ), on a string. As the problem begins, the wave f 1 ( x ) is mov- ing to the right at v 1 = +1 m/s and the wave f 2 ( x ) is moving to the left at v 2 =- 1 m/s. v 1 v 2 1 2 3 4 5 6 7 8 9 10-3-2-1 1 2 3 Amplitude(centimeter) Distance (meter) What is the shape of the wave on the string after 3 s? 1. 1 2 3 4 5 6 7 8 9 10-3-2-1 1 2 3 Distance (meter) practice 13 – GADHIA, TEJAS – Due: Apr 19 2007, 4:00 pm 2 2. 1 2 3 4 5 6 7 8 9 10-3-2-1 1 2 3 Distance (meter) 3. 1 2 3 4 5 6 7 8 9 10-3-2-1 1 2 3 Distance (meter) 4. 1 2 3 4 5 6 7 8 9 10-3-2-1 1 2 3 Distance (meter) 5. 1 2 3 4 5 6 7 8 9 10-3-2-1 1 2 3 Distance (meter) 6. 1 2 3 4 5 6 7 8 9 10-3-2-1 1 2 3 Distance (meter) 7. 1 2 3 4 5 6 7 8 9 10-3-2-1 1 2 3 Distance (meter) correct 8. 1 2 3 4 5 6 7 8 9 10-3-2-1 1 2 3 Distance (meter) 9. 1 2 3 4 5 6 7 8 9 10-3-2-1 1 2 3 Distance (meter) practice 13 – GADHIA, TEJAS – Due: Apr 19 2007, 4:00 pm 3 10. 1 2 3 4 5 6 7 8 9 10-3-2-1 1 2 3 Distance (meter) Explanation: The initial wave moving to the right is rep- resented with a dashed line and the eave mov- ing to the left is represented with a dotted line....
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## This note was uploaded on 03/09/2011 for the course PHY 303K taught by Professor Turner during the Spring '08 term at University of Texas.

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Practice 13 Solutions - practice 13 – GADHIA, TEJAS –...

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