University physics, waves, multiple choice.

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SUMMARY

The discussion focuses on solving a physics problem involving a cord with a mass of 40g and a tension of 19.2N, where the natural frequency is given as 10Hz. The length of the cord is calculated to be approximately 1.2125 meters, derived from the relationship between wave velocity, frequency, and wavelength. Additionally, the time taken for a wave to travel the length of the cord is determined to be 0.05 seconds. The solution utilizes the equations for wave velocity and wavelength, demonstrating the application of physics principles in problem-solving.

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  • Understanding of wave mechanics and wave equations
  • Familiarity with the concepts of tension and frequency in strings
  • Knowledge of basic algebra for manipulating equations
  • Ability to apply the formula for wave velocity, v = sqrt(FT/(m/L))
NEXT STEPS
  • Study the derivation of wave velocity in strings using tension and mass per unit length
  • Learn about the relationship between frequency, wavelength, and wave speed
  • Explore the concept of standing waves and their formation in fixed-end strings
  • Investigate the effects of varying tension and mass on the natural frequency of a string
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Students of physics, particularly those studying wave mechanics, as well as educators and tutors looking for problem-solving strategies in wave-related topics.

thinktoohard
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Homework Statement



A cord with a mass of 40g is tied between two supports with a tension of 19.2N. The natural frequency of the cord is 10Hz. Find the length of the cord

a.1.2m b.2m c.289m d.34cm

Using your answer from Question 3, how long does the wave take to travel from one end of the string to the other?

a.0.1s b.0.05s c.50s d.20s

Homework Equations



v=squrt(forcetension/(mass/length))
v=wavelength/Period=wavelength*frequency

The Attempt at a Solution



Knowns:
fixed ends, string.
mass = 0.040 kg
Force Tension = 19.2N
Natural Frequency = 10Hz
length of the cord = ?

Calculated:
Period = 0.1 s
Weight = 0.392 N

Other stuff:
Velocity = ?
Wavelength = 2L = ?

I've basically just stared at it and played around with everything I can think of which gets me no where close to an answer, for the past hour trying to figure out what to do, Made an account just to ask this forum about it.
 
Last edited:
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Hello, thinktoohard. Welcome to PF!

You need to show some attempt at a solution to receive help here.

You've got two "relevant equations" and one "other stuff equation" λ = 2L.

Show us your attempt at combining those equations to get a single equation for L in terms of the given quantities.
 
Thanks anyways I figured it out, Sub λ = 2L -> f = v/λ -> L = v/(2f), -> sub into v = sqrt.(ft/(m/L)) for -> v = sqrt.(FT/(m/(v/2f))) then isolate for v, gives you v = 24.25 m/s, -> v/2f = L -> L = 1.2125 -> L/v = 0.05 s.
 

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