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Ch. 6 - Applications of Integration
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243Not the one you use?Change textbook
Chapter 6, Problem 6.RE.9a

Fuel consumption A small plane in flight consumes fuel at a rate (in gal/min) given by
R'(t) ={ 4t^{1/3} if 0 ≤ t ≤ 8 (take-off)
2 if t> 0 (cruising)
a. Find a function R that gives the total fuel consumed, for 0≤t≤8.

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1
Identify the given rate of fuel consumption function for the time interval 0 \(\leq\) t \(\leq\) 8, which is R'(t) = 4t^{1/3}. This represents the rate of fuel consumption in gallons per minute during take-off.
Recall that to find the total fuel consumed function R(t), you need to integrate the rate function R'(t) with respect to time t over the interval from 0 to t.
Set up the integral: R(t) = \(\int\) 4t^{1/3} \, dt. This integral will give the total fuel consumed from time 0 up to time t during take-off.
Perform the integration by applying the power rule for integrals: \(\int\) t^{n} \, dt = \(\frac{t^{n+1}\)}{n+1} + C. Here, n = \(\frac{1}{3}\), so integrate accordingly and include the constant of integration C.
Use the initial condition R(0) = 0 (since no fuel is consumed at time zero) to solve for the constant C, ensuring the total fuel consumed function R(t) correctly models the situation.

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Key Concepts

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

Rate of Change and Derivatives

The rate of change represents how a quantity changes over time, often expressed as a derivative. In this problem, R'(t) is the rate of fuel consumption, showing how many gallons are used per minute at time t. Understanding derivatives helps interpret and work with rates in real-world contexts.
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Integration to Find Accumulated Quantity

Integration is the reverse process of differentiation and is used to find the total accumulated amount from a rate function. Here, integrating R'(t) over time gives the total fuel consumed, R(t), between 0 and 8 minutes. This concept connects rates to total quantities.
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Piecewise Functions

Piecewise functions define different expressions over different intervals. The fuel consumption rate R'(t) changes form at t=8, requiring careful handling of each interval separately. Understanding piecewise functions ensures correct application of integration and interpretation of the problem.
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Related Practice
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