# Spring Problem

#### timtng

When the tension is 18 N, a string 2.00 m long has a fundamental frequency of 150 Hz.
a.) What is the mass of the string?
b.) With what tension must the string be stretched so that it vibrates in three segments at 150 Hz?

This is what I came up with:
a.) f=v/2L, v=2Lf=2*2*150=600 m/s
v=sqrt(T/&mu;), v^2=T/&mu;, &mu;=T/v^2=18/600^2=.00005 kg/m
M=2*.00005=.0001 kg

b.) L=3&lambda;/2, 2=3&lambda;/2, &lambda;=4/3
v=f&lambda;=150*4/3=200 m/s
v^2=T/&mu;, T=&mu;*v^2=.00005*200^2=2 N

Am I working both problems correctly?

Thanks

Related Introductory Physics Homework Help News on Phys.org

#### Doc Al

Mentor
Your physics looks good. (I didn't check the arithmetic )

### Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving