# How can I pluck strings (with changing length) with constant energy?

• mt1815
mt1815
Homework Statement
I am doing an Extended Essay on Physics
Relevant Equations
n/a
Hi I am doing a physics investigation on the research question "If the string length changes (same tension) does the spread and amplitude of harmonics change?".

If I'm not mistaken, plucking energy should be a control variable. So, I want the energy of my plucks to remain consistent (through trials of changing length). Is there an easy way to accomplish this (at home) and measure the energy input (for further calculations)?

(edit)
I had an idea to attach a pendulum to attack the string with constant energy. But then I would not be able to measure the energy applied.

Last edited:
You might investigate the mechanisms of the harpsichord and pianoforte. They didn't call it a "softloud" for no reason.

berkeman

## 1. How can I ensure that the energy remains constant when plucking strings of different lengths?

To ensure that the energy remains constant when plucking strings of different lengths, you need to adjust the force applied to the string. The energy imparted to the string is proportional to the square of the displacement (amplitude) and the tension. By carefully controlling the displacement and considering the tension, you can maintain constant energy.

## 2. What role does string tension play in maintaining constant energy during plucking?

String tension is a critical factor in maintaining constant energy. The energy stored in a plucked string is proportional to both the tension and the square of the amplitude of the pluck. Therefore, for strings of different lengths, you must adjust the plucking force to account for changes in tension to keep the energy constant.

## 3. How can I measure the energy imparted to a plucked string?

The energy imparted to a plucked string can be measured by analyzing the string's vibration. This involves calculating the potential and kinetic energy of the vibrating string. The total energy is the sum of these energies and can be determined using equations that factor in the string's tension, length, mass per unit length, and the amplitude of vibration.

## 4. Does the material of the string affect how I should pluck it to maintain constant energy?

Yes, the material of the string affects its tension, density, and elasticity, which in turn influence the energy dynamics. Different materials will have different responses to plucking forces, so you will need to adjust the plucking force accordingly to maintain constant energy across strings of varying lengths and materials.

## 5. Are there any tools or devices that can help in plucking strings with constant energy?

Yes, there are tools and devices that can help, such as automated plucking mechanisms or robotic arms that can precisely control the force and displacement applied to the string. Additionally, force sensors and feedback systems can be used to adjust the plucking force in real-time to ensure constant energy is imparted to the string.

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