Old Homework 39 - portillo(gdp347 – oldhomework 39 –...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: portillo (gdp347) – oldhomework 39 – Turner – (58185) 1 This print-out should have 14 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 10.0 points Two similar tuning forks produce sound waves of the same 2 . 9 mPa amplitude. One tuning fork y 1 has a frequency 1044 s − 1 and the other y 2 has a frequency of 1160 s − 1 . These two tuning forks produce interference. + A + A- A-A T beat T wave y 1 y 2 y 1 + y 2 + A- A 3 T beat 6 T beat What is the number of beats per second that is heard? Correct answer: 116 Hz. Explanation: Let : A = 2 . 9 mPa , f 1 = 1044 s − 1 , and f 2 = 1160 s − 1 . +5 . 5- 5 . 5 A (mPa) t (milli-seconds) 8 . 6 ms 17 . 2 ms y 1 y 2 y 1 + y 2 +5 . 5- 5 . 5 A (mPa) t (milli-seconds) 25 . 8 ms 51 . 6 ms Two harmonic waves are described by y 1 = A cos( k x- ω 1 t ) and y 2 = A cos( k x- ω 2 t ) . f 2- f 1 2 = 58 s − 1 , f 1 + f 2 2 = 1102 s − 1 , T wave = 1 f 2- f 1 2 = 17 . 2 ms , ω 1 = 2 π f 1 = 2 π (1044 s − 1 ) = 6559 . 65 rad / s , ω 2 = 2 π f 2 = 2 π (1160 s − 1 ) = 7288 . 49 rad / s , ω 2- ω 1 2 = 364 . 425 rad / s , ω 2 + ω 1 2 = 6924 . 07 rad / s , portillo (gdp347) – oldhomework 39 – Turner – (58185) 2 and y 1 + y 2 = 2 A cos bracketleftbiggparenleftbigg ω 1- ω 2 2 parenrightbigg t bracketrightbigg × cos bracketleftbiggparenleftbigg ω 1 + ω 2 2 parenrightbigg t bracketrightbigg A = 2 A cos bracketleftbiggparenleftbigg ω 1- ω 2 2 parenrightbigg t bracketrightbiggvextendsingle vextendsingle vextendsingle vextendsingle max = 2 (2 . 9 mPa) · cos bracketleftbigg (- 364 . 425 rad / s) t bracketrightbiggvextendsingle vextendsingle vextendsingle vextendsingle max = 5 . 8 mPa , where A is the amplitude of the sum of the two waves y 1 + y 2 , and A is the amplitude of either wave y 1 or y 2 . The wave produced by the interference of two waves of frequencies f 2 and f 1 , respec- tively, has frequency f wave ≡ f 2- f 1 2 , where f 2 > f 1 = 1160 s − 1- 1044 s − 1 2 = 58 s − 1 , and the period T wave ≡ 1 f wave = 1 58 s − 1 = 17 . 2 ms ....
View Full Document

This note was uploaded on 01/25/2012 for the course CHEM 302 taught by Professor Mccord during the Spring '10 term at University of Texas.

Page1 / 6

Old Homework 39 - portillo(gdp347 – oldhomework 39 –...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online