Mathematics Grade 11 15 min

Time patterns

Time patterns

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1

Introduction & Learning Objectives

Learning Objectives Identify the key characteristics of a periodic function (amplitude, period, midline, phase shift) from a graph representing a time pattern. Model a real-world time-based pattern using a sinusoidal function (sine or cosine). Determine the formula of a periodic function given its graphical representation or key features. Calculate the period of a function from its formula and vice versa. Use a function model to predict future values in a time pattern. Interpret the parameters of a sinusoidal function in the context of a real-world problem. Have you ever noticed how the tides rise and fall, or how a pendulum swings back and forth with perfect regularity? 🌊 These are all functions of time! In this tutorial, we will explore how to use functions, specifically...
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Key Concepts & Vocabulary

TermDefinitionExample Periodic FunctionA function f(t) is periodic if its values repeat over regular intervals. Mathematically, f(t + T) = f(t) for all t, where T is a positive constant.The height of a spot on a spinning wheel over time is a periodic function. If it takes 2 seconds for a full rotation, its height at t=1 second will be the same as at t=3 seconds, t=5 seconds, and so on. Period (T)The smallest positive value of T for which a periodic function repeats. It represents the length of one full cycle, typically measured in units of time.If high tide occurs every 12.4 hours, the period of the tidal function is T = 12.4 hours. Amplitude (A)For a periodic function that oscillates around a central value, the amplitude is the maximum displacement or distance from that central value (th...
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Core Formulas

General Sinusoidal Function Model f(t) = A \sin(B(t - C)) + D \quad \text{or} \quad f(t) = A \cos(B(t - C)) + D This is the standard form for modeling periodic time patterns. 'A' is the amplitude, 'B' relates to the period, 'C' is the phase shift (horizontal), and 'D' is the midline (vertical shift). Use sine if the pattern starts at the midline and goes up; use cosine if it starts at a maximum. Period-Frequency Relationship T = \frac{2\pi}{B} \quad \text{and} \quad B = \frac{2\pi}{T} This formula connects the period (T) of the function with the parameter 'B' inside the sine or cosine argument. This is crucial for setting up the function to match a real-world time cycle. This formula assumes 't' is measured in a way...

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Sample Practice Questions

Challenging
Two sound waves are modeled by f(t) = sin(200Ï€t) and g(t) = sin(400Ï€t). How does the period of g(t) compare to the period of f(t)?
A.The period of g(t) is double the period of f(t).
B.The period of g(t) is the same as the period of f(t).
C.The period of g(t) is four times the period of f(t).
D.The period of g(t) is half the period of f(t).
Challenging
Consider the general function f(t) = Acos(Bt) + D. If the time it takes for the function to complete one cycle is doubled, what is the effect on the value of B?
A.is doubled.
B.is quadrupled.
C.is halved.
D.remains unchanged.
Challenging
A Ferris wheel with a radius of 15m is centered 18m above the ground. It completes one rotation every 60 seconds. A passenger gets on at the 3 o'clock position (level with the center) and is moving upwards. Which function h(t) correctly models the passenger's height?
A.h(t) = 15sin(Ï€t/30) + 18
B.h(t) = 15cos(Ï€t/30) + 18
C.h(t) = 18sin(Ï€t/30) + 15
D.h(t) = 15sin(30t/Ï€) + 18

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