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A loudspeaker diaphragm is producing a sound for 2.5 s by moving back and forth in simple harmonic motion. The angular frequency of the motion is \(7.54 \times 10^{4} \mathrm{rad} / \mathrm{s} .\) How many times does the diaphragm move back and forth?

Short Answer

Expert verified
The diaphragm moves back and forth approximately 30000 times.

Step by step solution

01

Understand Simple Harmonic Motion

In simple harmonic motion, an object moves back and forth along a path, completing one oscillation when it returns to its initial position and state.
02

Know the Formula for Angular Frequency

Angular frequency (\( \omega \)) is related to the frequency of oscillations (\( f \)) by the formula: \( \omega = 2 \pi f \). Here, \( \omega = 7.54 \times 10^4 \mathrm{rad/s} \).
03

Calculate the Frequency

Using the formula \( \omega = 2 \pi f \), solve for \( f \): \[ f = \frac{\omega}{2 \pi} = \frac{7.54 \times 10^4}{2 \pi} \]. Calculate \( f \) to find the number of cycles per second.
04

Compute Number of Cycles in Given Time

Once \( f \) (frequency in Hz) is calculated, multiply it by the time duration to find the total number of oscillations. The number of times the diaphragm moves back and forth in 2.5 s is \[ \text{Total Oscillations} = f \times 2.5 \].
05

Final Calculation

Using the value of \( f \) calculated earlier:\[ f \approx 1.2 \times 10^4 \text{ Hz} \]. Then, \[ \text{Total Oscillations} = 1.2 \times 10^4 \times 2.5 \approx 3 \times 10^4 \].

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Angular Frequency
Angular frequency is an intriguing concept that often appears in the study of oscillations and waves. It is denoted by the Greek letter omega (\( \omega \)) and shows how quickly an object moves through its cycle in radians per second. In simple harmonic motion, such as the motion of a loudspeaker diaphragm, angular frequency offers insight into the system's speed of oscillation. Imagine a circle with a point moving around it; the angular frequency tells you how fast this point completes its journey back to the start. The formula for angular frequency in relation to regular frequency \( f \) is \( \omega = 2\pi f \). This means that if you know how fast the object completes its cycles in terms of \( f \), you can find out how quickly it does so in terms of radians by multiplying \( f \) by \( 2\pi \). Knowing \( \omega \) helps us understand how rapid the oscillations are. In our problem, given \( \omega = 7.54 \times 10^4 \) rad/s, we can visualize that the diaphragm is indeed oscillating very rapidly.
Frequency Calculation
Calculating frequency is like discovering the tempo of a recurring event. Frequency, represented as \( f \), tells us how many cycles an oscillating object completes every second, measured in Hertz (Hz). To find the frequency from angular frequency, we use the familiar relationship \( \omega = 2\pi f \). Rearranging gives us \( f = \frac{\omega}{2\pi} \). For the loudspeaker diaphragm that's oscillating with \( \omega = 7.54 \times 10^4 \) rad/s, we plug this value into the formula:
  • \( f = \frac{7.54 \times 10^4}{2\pi} \)
By calculating this, we find the value of \( f \), which is approximately \( 1.2 \times 10^4 \) Hz. This reveals that the diaphragm completes about 12,000 cycles every second, making it a high-frequency sound generator. Understanding frequency in this context helps us comprehend not only the motion of sound waves but also their impact on what we hear.
Oscillation Count
The oscillation count is a straightforward yet essential concept in evaluating motion in time. It helps us quantify how many times an object, like our loudspeaker diaphragm, moves back and forth during a specified period. Once we have the frequency \( f \) from our earlier calculation, determining the total number of oscillations over a given time span is easy. We use the formula:
  • \( \text{Total Oscillations} = f \times \text{time} \)
For the diaphragm in question, with \( f \approx 1.2 \times 10^4 \) and a time duration of 2.5 s, the total oscillations can be calculated as follows:
  • \( \text{Total Oscillations} = 1.2 \times 10^4 \times 2.5 \approx 3 \times 10^4 \)
This means the diaphragm oscillates about 30,000 times in 2.5 seconds. Understanding oscillation count aids us in recognizing the intensity and duration of sound motion, essentially linking mathematical calculations with real-world sound production.

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Most popular questions from this chapter

A 6.8 -kg bowling ball is attached to the end of a nylon cord with a cross- sectional area of \(3.4 \times 10^{-5} \mathrm{m}^{2} .\) The other end of the cord is fixed to the ceiling. When the bowling ball is pulled to one side and released from rest, it swings downward in a circular arc. At the instant it reaches its lowest point, the bowling ball is \(1.4 \mathrm{m}\) lower than the point from which it was released, and the cord is stretched \(2.7 \times 10^{-3} \mathrm{m}\) from its unstrained length. What is the unstrained length of the cord? (Hint: When calculating any quantity other than the strain, ignore the increase in the length of the cord.)

A cylindrically shaped piece of collagen (a substance found in the body in connective tissue) is being stretched by a force that increases from 0 to \(3.0 \times 10^{-2} \mathrm{N}\). The length and radius of the collagen are, respectively, 2.5 and \(0.091 \mathrm{cm},\) and Young's modulus is \(3.1 \times 10^{6} \mathrm{N} / \mathrm{m}^{2}\). (a) If the stretching obeys Hooke's law, what is the spring constant \(k\) for collagen? (b) How much work is done by the variable force that stretches the collagen? (See Section 6.9 for a discussion of the work done by a variable force.)

A 30.0-kg block is resting on a fl at horizontal table. On top of this block is resting a 15.0-kg block, to which a horizontal spring is attached, as the drawing illustrates. The spring constant of the spring is 325 N/m. The coefficient of kinetic friction between the lower block and the table is 0.600, and the coefficient of static friction between the two blocks is 0.900. A horizontal force \(\overrightarrow{\mathbf{F}}\) is applied to the lower block as shown. This force is increasing in such a way as to keep the blocks moving at a constant speed. At the point where the upper block begins to slip on the lower block, determine (a) the amount by which the spring is compressed and (b) the magnitude of the force \(\overrightarrow{\mathbf{F}}\)

When responding to sound, the human eardrum vibrates about its equilibrium position. Suppose an eardrum is vibrating with an amplitude of \(6.3 \times 10^{-7}\) m and a maximum speed of \(2.9 \times 10^{-3} \mathrm{m} / \mathrm{s}\) (a) What is the frequency (in Hz) of the eardrum’s vibration? (b) What is the maximum acceleration of the eardrum?

A spring \((k=830 \mathrm{N} / \mathrm{m})\) is hanging from the ceiling of an elevator, and a 5.0-kg object is attached to the lower end. By how much does the spring stretch (relative to its unstrained length) when the elevator is accelerating upward at \(a=0.60 \mathrm{m} / \mathrm{s}^{2} ?\)

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