2015 AP Calculus AB Free Response #1

Allen Tsao The STEM Coach
23 Sept 201814:01
EducationalLearning
32 Likes 10 Comments

TLDRIn the video, Alan from Bottle Stem Coaching dives into AP Calculus 2015 free response questions, specifically focusing on a problem involving the flow of rainwater in a drain pipe. He introduces the use of GeoGebra graphing calculator to assist with the problem-solving process. The problem involves a partially blocked pipe with a given rate of water flow and drainage, and Alan demonstrates how to calculate the amount of water flowing into the pipe over an eight-hour period using integration. He also addresses how to determine if the water level in the pipe is increasing or decreasing at a specific time by comparing the flow rates. Alan further explores finding the time at which the water level in the pipe is at its minimum by identifying critical points and using a graphing calculator to solve for the minimum. Lastly, he discusses how to calculate the capacity of the pipe before it overflows for a given time period, without solving an equation involving integrals. The video is an educational walkthrough that combines mathematical concepts with practical application, making it engaging for viewers interested in calculus and problem-solving.

Takeaways
  • 📚 Alan is teaching AP Calculus using a 2015 free response question as an example.
  • 📈 Alan is experimenting with a GeoGebra graphing calculator for the first time during the lesson.
  • 🚰 The problem involves modeling the rate at which rainwater flows into a drain pipe, which is partially blocked.
  • ⏱️ The time variable T is measured in hours, ranging from 0 to 8 hours.
  • 💧 At time T=0, there are 30 cubic feet of water in the pipe.
  • 🧮 Alan demonstrates how to calculate the amount of rainwater flowing into the pipe using an integral from 0 to 8 hours.
  • ⛲️ The flow rate into the pipe is given by a function involving sine and polynomial terms.
  • 🔍 Alan discusses how to determine if the amount of water in the pipe is increasing or decreasing at a specific time, T=3 hours.
  • 📉 The pipe's water level decreases when the flow into the pipe is less than the flow out of the pipe.
  • 🔢 Alan calculates the critical points to find when the water level in the pipe is at a minimum.
  • 🕒 He identifies the time at which the water level is at its minimum, which is approximately 3.27 hours.
  • 🚫 For the last part, Alan is asked to determine the pipe's capacity before overflowing without solving an equation involving one or more integrals.
Q & A
  • What is the main topic of the video?

    -The main topic of the video is to continue with the AP Calculus 2015 free response questions, focusing on a problem involving the rate at which rainwater flows in a drain pipe.

  • What tool is Alan starting to use for graphing in this video?

    -Alan is starting to use GeoGebra graphing calculator to assist with the graphing calculator problem in the AP Calculus questions.

  • What is the function given to model the rate at which rainwater flows into the drain pipe?

    -The function given is not explicitly stated in the transcript, but it is described as a function of T (time in hours) with the domain of 0 ≤ T.

  • What is the initial condition given for the amount of water in the pipe at time T equals 0?

    -The initial condition given is that there are 30 cubic feet of water in the pipe at time T equals 0.

  • What is the integral Alan calculates to find out how much water flows into the pipe?

    -Alan calculates the integral of the rate function from 0 to 8 hours, which represents the amount of water flowing into the pipe during that time interval.

  • How does Alan determine if the amount of water in the pipe is increasing or decreasing at time T equals 3 hours?

    -Alan determines this by calculating the flow into the pipe (R of T) minus the flow out of the pipe (D of T) and checking if the result is greater than or less than zero.

  • What does Alan conclude about the flow of water in the pipe at time T equals 3 hours?

    -Alan concludes that the amount of water in the pipe is decreasing at time T equals 3 hours because the calculated flow is less than zero.

  • How does Alan find the time when the amount of water in the pipe is at a minimum?

    -Alan finds the time when the amount of water is at a minimum by setting the derivative of the flow rate function (R of T - D of T) equal to zero and solving for T.

  • What are the critical points Alan identifies for the minimum amount of water in the pipe?

    -Alan identifies T equals 0, T equals approximately 3.27, and T equals 8 as critical points where the derivative of the flow rate function is zero.

  • What is the minimum amount of water in the pipe, according to Alan's calculations?

    -The minimum amount of water in the pipe is approximately 27.96 cubic feet, which occurs at approximately 3.27 hours.

  • What is the final part of the problem that Alan discusses?

    -The final part of the problem Alan discusses is determining the time when the pipe will begin to overflow for T greater than 8, without solving an equation involving one or more integrals.

  • How does Alan approach the problem of finding the time when the pipe will overflow?

    -Alan sets up an equation where the amount of water in the pipe (A of W) at time W equals 50 cubic feet, indicating the pipe's capacity before overflowing.

Outlines
00:00
📚 Introduction to AP Calculus 2015 Free Response Questions

In this video segment, Alan introduces the topic of AP Calculus 2015 free response questions and mentions that he will be using a GeoGebra graphing calculator for the first time. He sets up a problem involving the rate of rainwater flow into a drain pipe, which is partially blocked, and explains the function modeling the rate in cubic feet per hour. The challenge is to calculate the amount of rainwater flowing into the pipe over an 8-hour period, starting with 30 cubic feet of water at time T equals 0.

05:07
🧮 Calculating the Flow and Rate of Water in the Pipe

Alan proceeds to calculate the flow of water into the pipe using an integral from 0 to 8 hours of the rate function, which is given as 20 times the sine of T squared divided by 35. He uses the GeoGebra calculator to find the integral's value and then discusses how to determine if the water level in the pipe is increasing or decreasing at a specific time, T equals 3 hours. He calculates the flow at this time and concludes that the water level is decreasing. He also explores finding the time when the water level in the pipe is at a minimum by setting the flow rate equal to the rate of decrease and solving for critical points.

10:10
📉 Determining the Minimum Water Level and Overflow Capacity

Alan calculates the minimum water level in the pipe by evaluating the integral from 0 to various critical points, including 0, 3.27, and 8 hours, and identifying the smallest value. He finds that the minimum occurs at approximately 3.27 hours with a water level of 27.96 cubic feet. Lastly, he addresses the scenario where the pipe can hold a certain amount of water before overflowing after T greater than 8 hours. He sets up the equation for the time when the pipe will begin to overflow without solving it, as it involves one or more integrals. The video segment concludes with a summary of the work done and an invitation for viewers to comment, like, or subscribe.

Mindmap
Keywords
💡AP Calculus
AP Calculus is a high school mathematics course that covers topics in calculus, which is the mathematical study of change, instantaneous rates of change, and the accumulation of quantities. In the video, the presenter is discussing AP Calculus 2015 free response questions, which are part of the AP examination in the subject. This indicates that the content is advanced and is being prepared for a standardized test.
💡GeoGebra
GeoGebra is a dynamic mathematics software that combines geometry, algebra, spreadsheets, graphing, statistics, and calculus. In the script, the presenter mentions starting to use GeoGebra as a graphing calculator, which suggests that it will be used to visualize and solve mathematical problems related to calculus, particularly when dealing with functions and their integrals.
💡Integral
An integral in calculus represents the area under a curve defined by a function. It is used to calculate quantities such as the amount of rainwater flowing into a pipe, as discussed in the video. The presenter performs an integral from zero to eight to find the total amount of water flowing into the pipe over a period of eight hours.
💡Rate of Flow
The rate of flow refers to the speed at which a substance, like rainwater in this case, moves through a system, such as a drain pipe. The video script describes a function that models the rate at which rainwater flows into a drain pipe, which is crucial for understanding the accumulation of water over time.
💡Partially Blocked Pipe
A partially blocked pipe is a scenario where the flow of a substance is impeded, but not completely stopped. In the context of the video, the pipe is partially blocked, allowing water to drain at a different rate at the other end. This creates a differential flow scenario that is central to the calculus problem being solved.
💡Cubic Feet
Cubic feet is a unit of measurement for volume that is commonly used to express the size of spaces or the volume of materials. In the script, the amount of water in the pipe is measured in cubic feet, which is essential for calculating the volume of water flowing into and out of the pipe.
💡Derivative
The derivative in calculus is a measure of how a function changes as its input changes. It is used to find critical points, such as local minima or maxima, which are important for understanding the behavior of the function over time. The presenter uses the derivative to find when the rate of flow into the pipe equals the rate of flow out of the pipe.
💡Critical Points
Critical points are points on a function where the derivative is either zero or undefined. They often represent points of interest, such as local maxima or minima. In the video, the presenter is interested in finding critical points to determine when the amount of water in the pipe is at a minimum.
💡Overflow
Overflow refers to a situation where a container, such as a pipe, has too much of a substance, causing it to spill over its edges. In the context of the video, the presenter is calculating the volume of water the pipe can hold before it begins to overflow, which is a practical application of integration in understanding the capacity of the system.
💡Free Response Questions
Free response questions are a type of open-ended question found in standardized tests, such as the AP Calculus exam. They require students to provide a detailed, step-by-step response to a problem. The video is focused on discussing and solving free response questions from a past AP Calculus exam.
💡Graphing Calculator
A graphing calculator is a specialized device that is used to perform mathematical functions, including graphing equations, solving equations, and performing calculations. In the script, the presenter mentions using a graphing calculator to solve the calculus problems, which is a common tool for visualizing and solving complex mathematical problems.
Highlights

Alan introduces the use of GeoGebra graphing calculator for AP Calculus problems.

The rate at which rainwater flows in a drain pipe is modeled by a function, with T measured in hours.

The pipe is partially blocked, affecting the rate of water drainage.

Initial condition: 30 cubic feet of water in the pipe at time T equals 0.

Part A of the problem asks for the calculation of the flow of rainwater into the pipe over an 8-hour interval.

Alan performs an integral calculation to find the flow into the pipe using GeoGebra.

The flow into the pipe is represented by the integral of 20 times sine of x squared divided by 35.

Alan explores whether the pipe's water level is increasing or decreasing at T equals three hours.

The flow is determined by the difference between the rate of water coming in (R of T) and the rate of water leaving (D of T).

A negative result at T equals three indicates the water level is decreasing.

To find the minimum water level in the pipe, Alan identifies critical points where the flow rate equals zero.

Alan uses the graphing calculator to find when the flow rate equals the outflow rate by plotting the functions and finding intersections.

Three potential minimum points are identified at T equals 0, 3.27, and 8.

Alan calculates the exact minimum by evaluating the integral from 0 to 3.27 and comparing it to other points.

The minimum water level in the pipe is determined to be at 3.27 hours with 27.96 cubic feet.

For T greater than 8, the pipe's capacity to hold water before overflowing is discussed without solving an equation involving integrals.

Alan sets up an equation to find the time 'W' when the pipe will begin to overflow, but does not solve it.

The scoring guidelines for the problem are reviewed, ensuring understanding of the decreasing flow and minimum points.

Alan acknowledges the learning process of using GeoGebra and invites feedback from viewers.

Transcripts
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