Linear density and tension problem

In summary: The tension is the speed of the wave squared (times the linear density of the string) times the linear density of the string.In summary, the conversation discusses the tension required to produce the note E on a violin string with a frequency of 329.6 Hz and a wavelength of 1.032 m. The tension can be calculated by using the speed of the wave in the string, which is determined by the string's linear density and the frequency of the wave. The tension needed for note E is 65081.316 N, and the difference in tension from the current wave frequency of 328.1 Hz is 591.019 N. However, there may be discrepancies with the given data, such as the mass of the
  • #1
HHH
34
0
The string on the violin with the highest pitch is the note E, which has a frequency of 329.6 Hz and a wavelength of 1.032 m. If the string has a mass of 180.0 g and a length of 32.0 cm and is currently producing a wave of frequency 328.1 Hz, how much do you need to change the tension in the
string to produce the note E? Assume string length, string mass, and wavelength remain unchanged in the tuning process.

The back of the book says 1.35 N and i keep getting around 591 N

1. Solve for tension in string
v = 328.1*1.032
v = 338.5992 m/s

Linear Density (u) = 0.18/0.32
Linear Density (u) = 0.5625 kg/m

338.5992= sqrt(Ft/0.5625)
338.5992^2 = Ft/0.5625
114649.418*0.5625 = Ft
64490.297 = Ft

2. Solve for tension required for note E
v = 329.6 *1.032
v = 340.1472 m/s

Linear Density (u) = 0.18/0.32
Linear Density (u) = 0.5625 kg/m

340.1472= sqrt(Ft/0.5625)
340.1472^2 = Ft/0.5625
115700.117*0.5625 = Ft
65081.316= Ft

3. Find the difference in tension
Ft = 65081.316 - 64490.297
Ft = 591.019
 
Last edited:
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  • #2
Your math seems fine, your textbook may be wrong. Unless I'm interpreting it incorrectly.
 
  • #3
HHH said:
The string on the violin with the highest pitch is the note E, which has a frequency of 329.6 Hz and a wavelength of 1.032 m. If the string has a mass of 180.0 g and a length of 32.0 cm and is currently producing a wave of frequency 328.1 Hz, how much do you need to change the tension in the
string to produce the note E? Assume string length, string mass, and wavelength remain unchanged in the tuning process.

Something is very wrong with the data. The 180 g mass is impossible for a violin string! If it is a steel string, it would mean about 5 mm thick! An E string should have of 0.2-0.3 mm diameter!
That 180 g =0.18 kg should be rather 0.18 g.

Also note that the given wavelength of pitch E (1.32 m) refers to air. The wavelength in the chord is different and defined by the length of the chord.
 
  • #4
ehild said:
Something is very wrong with the data. The 180 g mass is impossible for a violin string! If it is a steel string, it would mean about 5 mm thick! An E string should have of 0.2-0.3 mm diameter!
That 180 g =0.18 kg should be rather 0.18 g.

Also note that the given wavelength of pitch E (1.32 m) refers to air. The wavelength in the chord is different and defined by the length of the chord.
Is my process and math right? or no?
 
  • #5
HHH said:
Is my process and math right? or no?
The wavelength is twice the chord length. The speed of the wave in the chord is that length multiplied by the frequency.
 

Related to Linear density and tension problem

1. What is linear density and how is it related to tension?

Linear density refers to the mass per unit length of a linear object, such as a rope or cable. It is related to tension through the equation T = μg, where T is tension, μ is linear density, and g is the acceleration due to gravity. This equation shows that the tension in a linear object is directly proportional to its linear density.

2. How do I calculate linear density and tension?

Linear density can be calculated by dividing the mass of the object by its length. Tension can be calculated using the equation T = μg, as mentioned above. Alternatively, tension can also be calculated using Hooke's law, which states that the force applied to a linear object is directly proportional to its extension or compression. In this case, tension can be calculated by multiplying the spring constant by the change in length of the object.

3. How does linear density affect the strength of a linear object?

Linear density does not directly affect the strength of an object. However, objects with a higher linear density may experience higher tension when subjected to the same force, which can lead to a higher likelihood of breaking or stretching. The strength of an object also depends on other factors such as its material and structural design.

4. What are some real-world applications of understanding linear density and tension?

Understanding linear density and tension is important in various fields, such as engineering and physics. For example, it is used in the design and construction of bridges, cables, and other structures to ensure they can withstand the tension and weight they will be subjected to. It is also important in understanding the behavior of ropes and cables used in rock climbing and sailing.

5. How does temperature affect linear density and tension?

Temperature can affect the linear density and tension of an object by causing it to expand or contract. This change in size can alter the mass per unit length of the object, which in turn affects its tension. For example, a wire or cable may experience higher tension on a hot day due to its increased linear density caused by expansion. This is an important consideration in industries such as aerospace and construction.

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