Understanding Nodes and Frequencies in a Uniform String Under Tension

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SUMMARY

The discussion focuses on calculating the frequency of a uniform string under tension, specifically a string of length 2.5 m and mass 0.01 kg under a tension of 10 N. The fundamental frequency is determined using the formula ω = √(T/μ) * nπ/L, resulting in a value of 62.8319 radians/second for n=1. When a node is created by touching the string at 0.5 m, the effective length changes, and the participant questions whether to adjust the length to 2 m or to use n=5 for the new frequencies. Understanding the concept of nodes and their implications on frequency is crucial for further calculations.

PREREQUISITES
  • Understanding of wave mechanics and standing waves
  • Familiarity with tension and mass per unit length (μ) in strings
  • Knowledge of fundamental frequency calculations
  • Ability to interpret and draw standing wave patterns
NEXT STEPS
  • Research the concept of nodes and antinodes in standing waves
  • Learn about harmonic frequencies in fixed strings
  • Explore the effects of tension and mass on wave speed in strings
  • Study the derivation and application of the wave equation for strings
USEFUL FOR

Physics students, educators, and anyone interested in wave mechanics and the behavior of strings under tension will benefit from this discussion.

tourjete
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Homework Statement



A uniform string of length 2.5 m and mass 0.01 kg is placed under a tension of 10 N.

1. What is the frequency of the fundamental mode?

2. If the string is plucked and is then touched at a point 0.5 m from one end, creating a node, what frequencies persist?

Homework Equations



[tex]\omega[/tex] = [tex]\sqrt{T/\mu}[/tex]* n[tex]\pi[/tex]/L where [tex]\mu[/tex] = M/L

The Attempt at a Solution



I got the first part, I just plugged all the given information into the equation and used n=1 since it asked for the fundamental mode. I got 62.8319 radians/second.

I'm a bit lost as to what the concept of a node is. Do I just use the same equation again, but use L = 2.5 - .5 = 2 m? Or do I use n=5 since the string is now divided into fifths?
 
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Supposed the string is fixed at both ends, its length is equal to a half-wave in the fundamental mode. There is no motion at a node. Draw the standing wave when there is a node at 0.5 m from one end. Where are the other nodes?

ehild
 

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