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Ch. 4 - Applications of the Derivative
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243Not the one you use?Change textbook
Chapter 4, Problem 4.9.109b

107–110. {Use of Tech} Motion with gravity Consider the following descriptions of the vertical motion of an object subject only to the acceleration due to gravity. Begin with the acceleration equation a(t) = v' (t) = -g , where g = 9.8 m/s² .
b. Find the position of the object for all relevant times. 
A payload is released at an elevation of 400 m from a hot-air balloon that is rising at a rate of 10 m/s.

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Start with the given acceleration equation: a(t)=-g, where g=9.8 m/s2. Integrate the acceleration equation to find the velocity function v(t). The integral of -g with respect to t is -gt+C, where C is the constant of integration.
Determine the constant of integration C for the velocity function. At the moment the payload is released, the initial velocity is given as 10 m/s (the upward velocity of the hot-air balloon). Substitute v(0)=10 into the velocity equation to solve for C.
Once the velocity function v(t)=-gt+10 is determined, integrate it to find the position function s(t). The integral of -gt+10 with respect to t is -g2t2+10t+C, where C is the constant of integration.
Determine the constant of integration C for the position function. At the moment the payload is released, the initial position is given as 400 m. Substitute s(0)=400 into the position equation to solve for C.
Combine all the results to write the final position function s(t) in terms of t. This function will describe the vertical motion of the payload for all relevant times.

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Key Concepts

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

Acceleration due to Gravity

Acceleration due to gravity, denoted as 'g', is the rate at which an object accelerates towards the Earth when in free fall. On Earth, this value is approximately 9.8 m/s². This constant is crucial for understanding the motion of objects under the influence of gravity, as it determines how quickly their velocity changes over time.
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Derivatives Applied To Acceleration Example 2

Velocity and Position Functions

In calculus, the velocity of an object is the derivative of its position function with respect to time. To find the position of an object at any time, one must integrate the velocity function. In this context, the initial conditions, such as the initial height and the initial velocity, play a significant role in determining the position function.
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Using The Velocity Function

Kinematic Equations

Kinematic equations describe the motion of objects under constant acceleration. They relate displacement, initial velocity, final velocity, acceleration, and time. In this problem, these equations can be used to derive the position of the payload after it is released, taking into account its initial upward velocity and the downward acceleration due to gravity.
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Parameterizing Equations
Related Practice
Textbook Question

{Use of Tech} A damped oscillator The displacement of an object as it bounces vertically up and down on a spring is given by y(t) = 2.5e⁻ᵗ cos 2t, where the initial displacement is y(0) = 2.5 and y = 0 corresponds to the rest position (see figure). <IMAGE>


c. Find the time at which the object passes the rest position for the second time.

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Textbook Question

Suppose S = x + 2y is an objective function subject to the constraint xy = 50, for x > 0 and y > 0.

b. Find the absolute minimum value of S subject to the given constraint.

Textbook Question

Cylinder in a cone A right circular cylinder is placed inside a cone of radius R and height H so that the base of the cylinder lies on the base of the cone.


b. Find the dimensions of the cylinder with maximum lateral surface area (area of the curved surface).

Textbook Question

{Use of Tech} Fixed points of quadratics and quartics Let f(x) = ax(1 -x), where a is a real number and 0 ≤ a ≤ 1. Recall that the fixed point of a function is a value of x such that f(x) = x (Exercises 48–51). 


b. Consider the polynomial g(x) = f(f(x)). Write g in terms of a and powers of x. What is its degree?

Textbook Question

{Use of Tech} Demand functions and elasticity Economists use demand functions to describe how much of a commodity can be sold at varying prices. For example, the demand function D(p) = 500 - 10p says that at a price of p = 10, a quantity of D(10) = 400 units of the commodity can be sold. The elasticity E = dD/dp p/D of the demand gives the approximate percent change in the demand for every 1% change in the price. (See Section 3.6 or the Guided Project Elasticity in Economics for more on demand functions and elasticity.)


b. If the price is \$12 and increases by 4.5%, what is the approximate percent change in the demand? 

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Textbook Question

Explain why or why not Determine whether the following statements are true and give an explanation or counterexample.


c. If f(x) = mx + b, then the linear approximation to f at any point is L(x) = f(x).