Finding mass per unit length for stretched strng given tension?

In summary, the conversation involved solving for the mass per unit length of a stretched string given the tension and other variables such as amplitude, wavelength, angular frequency, and wave velocity. The individual was able to solve the problem using the wave equation and also discovered another method involving the relationship between wave speed, tension, and density.
  • #1
coffeem
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[SOLVED] Finding mass per unit length for stretched strng given tension?

A transverse wave on a stretched string under Tension = 5N is defined by the equation:

y(x,t) = 0.1cos(2pi/5(x - 10t)

Find:

a) amplitude = 0.1 m

b) wavelength = 0.4 m

c) angular frequency = 4 rad/s

d) wave velocity = 0.1. m/s

e) mass per unit length ?

f) for t = 0, sketch how y varies with x. ?


I can do the first 4 parts be using the solution to the wave equation. Any ideas on how to do the other two bits? thanks.
 
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  • #2
Hey thanks for anyone for looking at this. However I have been able to solve it another way. If anyone is interested the answer is:

wave speed v relates tension and density:

v = root(T/rho)

and you can set t=0 in that equation and you have something like y=acos(kx)
 
  • #3


Based on the given information, the mass per unit length of the stretched string can be calculated using the following formula:

μ = (T/υ^2) * λ

Where,

μ = mass per unit length

T = tension in the string

υ = wave velocity

λ = wavelength

Substituting the values from the given information, we get:

μ = (5N / (0.1 m/s)^2) * 0.4 m

μ = 200 kg/m

Therefore, the mass per unit length for the stretched string is 200 kg/m.

For t = 0, the equation becomes:

y(x,0) = 0.1cos(2pi/5x)

This represents a simple harmonic motion with an amplitude of 0.1 m and a wavelength of 0.4 m. The graph of this function would be a cosine wave with an amplitude of 0.1 and a period of 0.4 m. The wave would start at the origin and oscillate between positive and negative values with a period of 0.4 m.

 

1. What is meant by "mass per unit length" in the context of a stretched string?

"Mass per unit length" refers to the amount of mass present in a given length of the string. It is typically measured in units of kilograms per meter (kg/m) or grams per centimeter (g/cm).

2. How is tension related to the mass per unit length of a stretched string?

In general, the greater the tension applied to a string, the greater the mass per unit length will be. This is because a higher tension results in a greater amount of force being applied to the string, which causes it to stretch and therefore increases its mass per unit length.

3. How do you find the mass per unit length of a stretched string?

To find the mass per unit length of a stretched string, you will need to know the tension applied to the string and its length. From there, you can use the equation mass per unit length = tension/length to calculate the value.

4. What units are typically used to express the mass per unit length of a stretched string?

The mass per unit length of a stretched string is typically expressed in either kilograms per meter (kg/m) or grams per centimeter (g/cm). However, other units such as pounds per foot (lb/ft) may also be used depending on the context.

5. Why is it important to know the mass per unit length of a stretched string?

Knowing the mass per unit length of a stretched string is important for understanding its physical properties and behavior. It can also be useful in various scientific and engineering applications, such as designing musical instruments or calculating the tension needed for certain tasks.

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