PHYS 1900-001
Acoustics and Sound Week 3 Assessment
Submit as a Word document in Blackboard. DO NOT SUBMIT AS A PDF.
Put you name and the assessment # at the top of the page.
Title your file “Last name, Assessment 3”
Cite any sources you use.
1. (50 pts) In the first day demonstration, you observed that two different sized violins had the same pitch (frequency), even though the small violin had shorter strings.
Using the frequency of a string equation, explain the two conditions that would cause the frequency of the small violin to be the same as the full-sized violin.
2. (50 pts) Sound travels at 1007 m/s in helium.
a. Your voice sounds higher after you have inhaled the helium from a party balloon. Explain why this happens using the wave formula.
b. The frequency of a Helmholtz resonator also increases if you use helium instead of air as the gas. Explain why this happens using the Helmholtz Resonator formula.
Extra credit (20 pts) – Choose one:
Design an experiment that would show how changes in linear mass density would affect the frequency of a string.
OR
You are building a Monochord – a one stringed musical instrument. You use a string that is 1 mm in diameter. You then change to a string that is ¼ the diameter of the original, made of the same material, with the same tension and length.
Using the frequency of a string formula, explain why the new frequency would be 4 times the frequency of the original string.
Hint - volume of a string = area x length. Area = pr2