Trig Functions: The Ferris Wheel

Arnold Tutoring
19 May 201506:25
EducationalLearning
32 Likes 10 Comments

TLDRThis educational video offers a clear guide on solving trigonometry word problems, particularly those involving circular motion like a Ferris wheel. The presenter introduces a general form for trig equations, emphasizing transformations in alphabetical order: vertical stretch (a), horizontal stretch (b), horizontal shift (c), and vertical shift (d). Using a Ferris wheel with a 17-meter diameter and a 25-second ascent as an example, the video demonstrates how to calculate these variables. It concludes with determining the trig function type (sine or cosine) and adjusting for the starting point, making it a practical resource for tackling similar trigonometric problems.

Takeaways
  • πŸ“š The video is about solving trigonometric word problems and developing trigonometric equations from them.
  • 🎑 The example used in the video is a Ferris wheel, which is a clue that trigonometry will be involved due to its circular motion.
  • πŸ“‰ The general form of a trigonometric equation is introduced as \( A \sin(B(t - C)) + D \), which includes transformations for amplitude (A), period (B), phase shift (C), and vertical shift (D).
  • πŸ” The amplitude (A) is determined by calculating the distance from the middle of the motion to the maximum point, which is \( \frac{\text{max} - \text{min}}{2} \).
  • ⏱ The period (B) is related to the timing of the motion and is calculated as \( \frac{2\pi}{\text{period of function}} \).
  • πŸ“ The vertical shift (D) is found by taking the average of the maximum and minimum values, which is \( \frac{\text{max} + \text{min}}{2} \).
  • πŸ”’ For the given Ferris wheel problem, the diameter is 17 meters, and the rider boards from a platform 2 meters off the ground, leading to a maximum height of 19 meters.
  • ⏳ The time it takes for the Ferris wheel to reach the top from the bottom is 25 seconds, which helps determine the period and the value of B.
  • πŸ“ The phase shift (C) and the function type (sine or cosine) are determined by the starting point of the motion; in this case, starting at the minimum suggests using cosine.
  • πŸ”„ To adjust the starting point of the cosine function from the maximum to the minimum, a negative sign is applied to the amplitude A, and no horizontal translation is needed.
  • πŸ’Œ The video concludes with an invitation to send more questions to Arnold Tutoring for further assistance.
Q & A
  • What is the significance of recognizing trigonometric functions in problems involving circular motion?

    -Trigonometric functions are significant in circular motion problems because they model the sinusoidal behavior of objects moving up and down in a periodic manner, such as a Ferris wheel or waves.

  • What is the general form of a trigonometric equation according to the video?

    -The general form of a trigonometric equation is A*sin(B*(X-C))+D, where A represents the vertical stretch/amplitude, B is related to the timing or period, C is the horizontal shift, and D is the vertical shift.

  • Why is it useful to apply transformations in alphabetical order when dealing with trigonometric equations?

    -Applying transformations in alphabetical order helps systematically identify and apply each transformation, making it easier to understand and solve the equations.

  • What is the diameter of the Ferris wheel mentioned in the video?

    -The diameter of the Ferris wheel mentioned in the video is 17 meters.

  • How high is the platform from the ground where the Ferris wheel boarding occurs?

    -The platform from where the Ferris wheel boarding occurs is 2 meters off the ground.

  • What is the time it takes for the Ferris wheel to reach the top from the bottom?

    -It takes 25 seconds for the Ferris wheel to reach the top from the bottom.

  • How is the amplitude (A) of a trigonometric function related to the maximum and minimum values in the context of the Ferris wheel?

    -The amplitude (A) is half the distance from the maximum to the minimum value. In the context of the Ferris wheel, it is calculated as (maximum height - minimum height) / 2.

  • What does B represent in the context of the trigonometric equation and how is it calculated?

    -B represents the timing or frequency of the function and is calculated as 2Ο€ divided by the period of the function. In the context of the Ferris wheel, the period is the total time it takes to complete one full cycle.

  • How is the vertical shift (D) determined for the trigonometric equation representing the Ferris wheel?

    -The vertical shift (D) is determined by taking the average of the maximum and minimum values, which is calculated as (maximum height + minimum height) / 2.

  • Why is the cosine function chosen over the sine function for the horizontal translation (C) in the Ferris wheel example?

    -The cosine function is chosen because the rider starts at the minimum height (bottom of the Ferris wheel), and cosine naturally starts at its maximum. By making the amplitude negative, the function is flipped to start at the minimum, matching the situation.

  • What is the horizontal translation (C) for the trigonometric function representing the Ferris wheel's height over time?

    -Since the cosine function is used and it's flipped to start at the minimum, there is no horizontal translation (C = 0) in this case.

Outlines
00:00
🎑 Trigonometry in Ferris Wheel Motion

This paragraph introduces a trigonometry problem involving a Ferris wheel, which is a clear indicator of a trigonometric function due to its circular motion. The speaker begins by outlining the general form of a trigonometric equation, emphasizing the importance of transformations such as vertical stretch (a), horizontal stretch (b), horizontal shift (c), and vertical shift (d). The example uses a Ferris wheel with a 17-meter diameter and a starting height of 2 meters above the ground. The key to solving the problem is to establish an equation that represents the height of a rider as a function of time. The amplitude (a) is calculated as half the distance between the maximum and minimum height, the period (b) is related to the time it takes for one complete cycle, and the vertical shift (d) is the average of the maximum and minimum heights. The paragraph concludes with the development of the equation using the given values for a, b, and d.

05:01
πŸ“‰ Understanding Cosine and Sine Functions for Trigonometric Equations

The second paragraph delves deeper into the specifics of choosing between sine and cosine functions for the Ferris wheel scenario. It explains that the starting point of the function is crucial in determining whether to use sine or cosine. Since the Ferris wheel starts at its lowest point, the cosine function is more appropriate because it naturally starts at its maximum. To adjust the cosine function to start at the minimum, the speaker suggests flipping the function by making the amplitude negative. This transformation aligns the function with the scenario where the ride begins at the bottom. The paragraph also touches on the ease of identifying and solving trigonometric problems related to circular motion and encourages the use of sine and cosine to simplify the process. The speaker invites viewers to reach out for more questions, providing an email address for further support.

Mindmap
Keywords
πŸ’‘Trigonometry
Trigonometry is a branch of mathematics that deals with the relationships between the sides and angles of triangles, particularly right-angled triangles. In the context of the video, trigonometry is used to model periodic phenomena such as the motion of a Ferris wheel, which moves in a circular path. The script mentions trigonometry as a way to solve word problems involving sinusoidal functions, which are essential for representing the up and down motion of the Ferris wheel.
πŸ’‘Trig Functions
Trig functions, or trigonometric functions, are mathematical functions that relate the angles of a triangle to the lengths of its sides. In the video, trig functions are used to describe the height of a rider on a Ferris wheel over time. The sine and cosine functions are specifically highlighted as they are the primary functions used to model periodic phenomena like the motion depicted in the video.
πŸ’‘Sine
The sine function is one of the fundamental trigonometric functions. It is used to model periodic phenomena, such as the oscillation of a wave or the motion of a point on a circle. In the video, sine is considered as a potential function to represent the height of a rider on a Ferris wheel as a function of time, with the understanding that it oscillates between -1 and 1.
πŸ’‘Cosine
The cosine function is another fundamental trigonometric function, similar to sine but with a phase shift. It is also used to model periodic phenomena. The video discusses the use of cosine to represent the height of a rider on a Ferris wheel, especially when considering the starting point of the motion at the minimum height, which is the bottom of the Ferris wheel.
πŸ’‘Ferris Wheel
A Ferris wheel is a large, vertically rotating wheel that carries passengers in passenger cabins around a central hub. In the video, the Ferris wheel serves as a real-world example to demonstrate how trigonometry can be applied to model the height of a rider as a function of time. The diameter and the time taken to reach the top from the bottom are key details used to develop the trigonometric equation.
πŸ’‘Amplitude
In the context of trigonometry, amplitude refers to the maximum displacement of a periodic wave from its equilibrium or mean position. In the video, amplitude is calculated as half the distance between the maximum and minimum heights of the Ferris wheel, which is essential for determining the 'a' value in the general form of the trig equation.
πŸ’‘Period
The period of a function is the length of one complete cycle of the function's values. In the video, the period is discussed in relation to the time it takes for the Ferris wheel to complete one full rotation, which is crucial for determining the 'B' value in the trigonometric equation.
πŸ’‘Vertical Shift
A vertical shift in the context of functions refers to moving the graph of a function up and down without changing its shape. In the video, the vertical shift 'D' is calculated as the average of the maximum and minimum heights of the Ferris wheel, which is necessary to adjust the baseline of the trigonometric function to match the Ferris wheel's motion.
πŸ’‘Horizontal Shift
A horizontal shift refers to moving the graph of a function left or right without changing its shape. In the video, the horizontal shift 'C' is discussed in the context of translating the trigonometric function to match the starting position of the Ferris wheel's motion, which is at the bottom of the wheel.
πŸ’‘General Form
The general form of a trigonometric equation is a template that includes variables for amplitude ('a'), horizontal stretch/compression ('b'), horizontal shift ('c'), and vertical shift ('d'). In the video, the general form is used to systematically apply these transformations to develop a trigonometric equation that models the height of a rider on a Ferris wheel over time.
πŸ’‘Horizontal Stretch/Compression
Horizontal stretch or compression refers to the process of making a graph of a function wider or narrower without changing its shape vertically. In the video, this concept is related to the 'B' value and is used to adjust the timing of the trigonometric function to match the period of the Ferris wheel's rotation.
Highlights

The video demonstrates how to deal with trigonometric word problems and develop trigonometric equations from them.

Trigonometry is implied in problems involving circular motion, such as a Ferris wheel, waves, or petals moving in a circular pattern.

The general form of a trigonometric equation is introduced with variables A, B, C, and D representing transformations.

A represents the vertical stretch or amplitude of the trigonometric function.

B is associated with the timing or horizontal stretch of the function, calculated as 2Ο€ over the period.

C is the horizontal shift, which can be more complex to determine than A, B, and D.

D represents the vertical shift of the function, calculated as the average of the maximum and minimum values.

An example of a Ferris wheel with a 17-meter diameter and a 2-meter platform height is used to illustrate the process.

The maximum height reached by the Ferris wheel is calculated to be 19 meters.

The time taken to reach the top from the bottom is given as 25 seconds, indicating a period of 50 seconds for one complete cycle.

The amplitude (A) of the trigonometric function is determined to be 8.5 meters.

The period (B) of the function is calculated as Ο€/25 based on the 25-second interval to reach the top.

The vertical shift (D) is determined to be 10.5 meters, shifting the wheel upward.

The choice between sine and cosine functions is made based on the starting point of the motion.

A cosine function is chosen and flipped to start at the minimum point, representing boarding at the bottom of the Ferris wheel.

The horizontal translation (C) is determined to be zero since the cosine function is flipped to start at the bottom.

The final trigonometric equation representing the height of the rider over time is developed using the determined values of A, B, C, and D.

The video emphasizes the ease of recognizing and solving trigonometric problems involving circular motion.

Contact information for further questions is provided, encouraging viewers to reach out for assistance.

Transcripts
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