High School

A string is fixed at both ends. The mass of the string is 0.0010 kg, and the length is 3.35 m. The string is under a tension of 195 N. The string is driven by a variable frequency source to produce standing waves.

Find the wavelengths and frequencies of the first four modes of standing waves.

Answer :

The wavelengths and frequencies of the first four modes of standing waves on the string are approximately: Mode 1 - λ = 6.70 m, f = 120.6 Hz; Mode 2 - λ = 3.35 m, f = 241.2 Hz; Mode 3 - λ ≈ 2.23 m, f ≈ 362.2 Hz; Mode 4 - λ = 3.35 m, f = 241.2 Hz.

To find the wavelengths and frequencies of the first four modes of standing waves on the string, we can use the formula:

λ = 2L/n

Where:

λ is the wavelength,

L is the length of the string, and

n is the mode number.

The frequencies can be calculated using the formula:

f = v/λ

Where:

f is the frequency,

v is the wave speed (determined by the tension and mass per unit length of the string), and

λ is the wavelength.

Given:

Mass of the string (m) = 0.0010 kg

Length of the string (L) = 3.35 m

Tension (T) = 195 N

First, we need to calculate the wave speed (v) using the formula:

v = √(T/μ)

Where:

μ is the linear mass density of the string, given by μ = m/L.

μ = m/L = 0.0010 kg / 3.35 m = 0.0002985 kg/m

v = √(195 N / 0.0002985 kg/m) = √(652508.361 N/m^2) ≈ 808.03 m/s

Now, we can calculate the wavelengths (λ) and frequencies (f) for the first four modes (n = 1, 2, 3, 4):

For n = 1:

λ₁ = 2L/1 = 2 * 3.35 m = 6.70 m

f₁ = v/λ₁ = 808.03 m/s / 6.70 m ≈ 120.6 Hz

For n = 2:

λ₂ = 2L/2 = 3.35 m

f₂ = v/λ₂ = 808.03 m/s / 3.35 m ≈ 241.2 Hz

For n = 3:

λ₃ = 2L/3 ≈ 2.23 m

f₃ = v/λ₃ = 808.03 m/s / 2.23 m ≈ 362.2 Hz

For n = 4:

λ₄ = 2L/4 = 3.35 m

f₄ = v/λ₄ = 808.03 m/s / 3.35 m ≈ 241.2 Hz

Therefore, the wavelengths and frequencies of the first four modes of standing waves on the string are approximately:

Mode 1: Wavelength (λ) = 6.70 m, Frequency (f) = 120.6 Hz

Mode 2: Wavelength (λ) = 3.35 m, Frequency (f) = 241.2 Hz

Mode 3: Wavelength (λ) ≈ 2.23 m, Frequency (f) ≈ 362.2 Hz

Mode 4: Wavelength (λ) = 3.35 m, Frequency (f) = 241.2 Hz

To know more about frequency refer here

https://brainly.com/question/29739263#

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