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Ch. 4 - Graphs of the Circular Functions
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161Not the one you use?Change textbook
Chapter 5, Problem 3

An object in simple harmonic motion has position function s(t), in inches, from an equilibrium point, as follows, where t is time in seconds.
𝒮(t) = 5 cos 2t
What is the frequency?

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1
Identify the general form of the position function for simple harmonic motion, which is usually written as \(s(t) = A \cos(\omega t)\), where \(A\) is the amplitude and \(\omega\) is the angular frequency in radians per second.
From the given function \(s(t) = 5 \cos 2t\), recognize that the angular frequency \(\omega\) is 2 radians per second.
Recall the relationship between angular frequency \(\omega\) and frequency \(f\): \(\omega = 2\pi f\).
Rearrange the formula to solve for frequency: \(f = \frac{\omega}{2\pi}\).
Substitute the value of \(\omega = 2\) into the formula to express the frequency as \(f = \frac{2}{2\pi}\), which simplifies the expression for frequency.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Simple Harmonic Motion (SHM)

Simple Harmonic Motion describes oscillatory motion where an object moves back and forth around an equilibrium point in a sinusoidal pattern. The position function s(t) typically involves sine or cosine functions, representing displacement over time.
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Angular Frequency (ω)

Angular frequency ω is the rate of change of the phase of the sinusoidal function in radians per second. In the function s(t) = A cos(ωt), ω determines how fast the oscillations occur and is related to the frequency by ω = 2πf.
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Frequency and its Relation to Angular Frequency

Frequency (f) is the number of oscillations per second, measured in Hertz (Hz). It is calculated from angular frequency using the formula f = ω / (2π). Knowing ω allows you to find how many complete cycles occur each second.
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