Table of contents
- 0. Functions7h 52m
- Introduction to Functions16m
- Piecewise Functions10m
- Properties of Functions9m
- Common Functions1h 8m
- Transformations5m
- Combining Functions27m
- Exponent rules32m
- Exponential Functions28m
- Logarithmic Functions24m
- Properties of Logarithms34m
- Exponential & Logarithmic Equations35m
- Introduction to Trigonometric Functions38m
- Graphs of Trigonometric Functions44m
- Trigonometric Identities47m
- Inverse Trigonometric Functions48m
- 1. Limits and Continuity2h 2m
- 2. Intro to Derivatives1h 33m
- 3. Techniques of Differentiation3h 18m
- 4. Applications of Derivatives2h 38m
- 5. Graphical Applications of Derivatives6h 2m
- 6. Derivatives of Inverse, Exponential, & Logarithmic Functions2h 37m
- 7. Antiderivatives & Indefinite Integrals1h 26m
- 8. Definite Integrals4h 44m
- 9. Graphical Applications of Integrals2h 27m
- 10. Physics Applications of Integrals 2h 22m
4. Applications of Derivatives
Motion Analysis
Problem 3.6.55c
Textbook Question
{Use of Tech} Spring oscillations A spring hangs from the ceiling at equilibrium with a mass attached to its end. Suppose you pull downward on the mass and release it 10 inches below its equilibrium position with an upward push. The distance x (in inches) of the mass from its equilibrium position after t seconds is given by the function x(t) = 10sin t−10cos t, where x is positive when the mass is above the equilibrium position. <IMAGE>
c. At what times is the velocity of the mass zero?

1
To find when the velocity of the mass is zero, we first need to determine the velocity function. The velocity is the derivative of the position function x(t) with respect to time t.
Given the position function x(t) = 10sin(t) - 10cos(t), we differentiate it to find the velocity function v(t). The derivative of sin(t) is cos(t), and the derivative of cos(t) is -sin(t).
Applying these derivatives, the velocity function v(t) is: v(t) = d/dt [10sin(t) - 10cos(t)] = 10cos(t) + 10sin(t).
To find when the velocity is zero, we set the velocity function equal to zero: 10cos(t) + 10sin(t) = 0.
Solve the equation 10cos(t) + 10sin(t) = 0 for t. This involves finding the values of t where the sum of the cosine and sine terms equals zero, which can be done by using trigonometric identities or algebraic manipulation.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Velocity and Its Calculation
Velocity is the rate of change of position with respect to time. In calculus, it is found by taking the derivative of the position function. For the given function x(t) = 10sin(t) - 10cos(t), the velocity function v(t) can be determined by differentiating x(t) with respect to t, which will provide the times when the mass is momentarily at rest.
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Finding Critical Points
Critical points occur where the derivative of a function is zero or undefined. In the context of the velocity function, setting v(t) = 0 will help identify the times when the mass's velocity is zero, indicating moments when the mass changes direction. This is essential for understanding the oscillatory motion of the mass attached to the spring.
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Trigonometric Functions and Their Properties
The position function x(t) involves sine and cosine functions, which are periodic and have specific properties regarding their maxima, minima, and zeros. Understanding the behavior of these trigonometric functions is crucial for analyzing the motion of the mass, particularly in determining the intervals of time when the velocity is zero, as these functions oscillate between -1 and 1.
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