Examkin

Question

Difficulty: MediumIdentifying Independent, Dependent, and Controlled Variables

A team of acoustic engineers conducted an experiment to evaluate how the sound dampening efficiency of polyurethane foam panels is impacted by the concentration of embedded micro-perforated ceramic beads. Five panels of identical dimensions (50 cm×50 cm×5 cm50\text{ cm} \times 50\text{ cm} \times 5\text{ cm}) were manufactured with varying concentrations of ceramic beads (0%0\%, 5%5\%, 10%10\%, 15%15\%, and 20%20\% by mass). Each panel was placed between a sound generator emitting a constant 1-kHz1\text{-kHz} sine wave tone at 90 dB90\text{ dB} and a decibel sensor positioned 1.0 m1.0\text{ m} away in an anechoic chamber held at 20∘C20^\circ\text{C}. The decibel sensor measured the acoustic absorption coefficient (α\alpha) of each panel. In this experiment, which factor served as the independent variable?

  1. The concentration of micro-perforated ceramic beads embedded in the foam panelsAnswer
  2. B
    The acoustic absorption coefficient measured by the decibel sensor
  3. C
    The 90-dB90\text{-dB} sound intensity level emitted by the generator
  4. D
    The 20∘C20^\circ\text{C} ambient temperature maintained within the anechoic chamber

Answer

The concentration of micro-perforated ceramic beads embedded in the foam panels is the independent variable.
The independent variable is the condition intentionally varied by the researchers. In this experiment, the engineers altered the concentration of micro-perforated ceramic beads (0%0\% to 20%20\%) to observe its effect on acoustic absorption.

Step-by-Step Solution

1
Identify the factor intentionally altered across experimental groups.
The engineers varied the concentration of ceramic beads from 0%0\% to 20%20\% across five distinct panels.
The variable systematically changed by the researchers to test its effect is defined as the independent variable.
2
Distinguish between the tested condition and measured outcome.
The measured output is the acoustic absorption coefficient, which depends on the bead concentration.
The measured result is the dependent variable, while constant factors (decibel level, panel dimensions, temperature) are controlled variables.

Key Concept

Independent vs. Dependent and Controlled Variables
Estimated Time:1m 0s
Rate this question

Topics

Identifying Independent, Dependent, and Controlled Variables

More questions from this topic