Related Rates - Gravel Dumped Into Conical Tank Problem

The Organic Chemistry Tutor
28 Feb 201814:57
EducationalLearning
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TLDRThe transcript describes two related rates problems involving cones. The first problem calculates the rate of change of the height of a conical pile of gravel, given the volume rate and the relationship between the base diameter and height. The second problem determines the rate of water flow into an inverted conical tank, considering the rate of water leakage and the dimensions of the tank. Both problems use mathematical modeling and differentiation to find the rates, resulting in 1/(18ฯ€) feet per minute for the gravel pile's height increase and 3358 cubic centimeters per minute for the water flow into the tank.

Takeaways
  • ๐Ÿ“ The problem involves a conical pile of gravel formed by a conveyor belt, with the rate of volume increase being 50 cubic feet per minute.
  • ๐Ÿ”„ The diameter of the base of the cone is always five times the height of the pile, providing a relationship between the dimensions of the cone.
  • ๐Ÿ“ˆ The goal is to find the rate at which the height of the pile is increasing when the pile is 12 feet high.
  • ๐Ÿ”ข The volume of a cone is given by the formula (1/3)ฯ€rยฒh, which is used to relate the volume change to the dimensions of the cone.
  • ๐Ÿ“š The problem requires differentiating the volume equation with respect to time to find the rate of change of the height (dh/dt).
  • ๐Ÿ”ง The relationship between the radius (r) and height (h) of the cone is used to eliminate one variable and solve for the other.
  • ๐Ÿงฎ When h is 12 feet, the calculation yields a rate of increase for the height (dh/dt) of 1/(18ฯ€) feet per minute.
  • ๐Ÿ’ง The second problem involves an inverted conical tank with water leaking out at a rate of 7,500 cubic centimeters per minute.
  • ๐Ÿบ The height of the water in the tank is 0.25 meters, and the rate at which the water level is falling is 15 centimeters per minute.
  • ๐Ÿ”„ The task is to find the rate at which water is flowing into the tank, considering both the inflow and outflow.
  • ๐Ÿ“ˆ The volume change equation for the tank is adapted to account for the falling water level, with the radius (r) expressed in terms of the height (h).
  • ๐Ÿงฎ By solving the net volume flow rate equation, the rate at which water is flowing into the tank is found to be 3,358 cubic centimeters per minute.
Q & A
  • What is the rate at which gravel is falling off the conveyor belt?

    -The gravel is falling off the conveyor belt at a rate of 50 cubic feet per minute.

  • What is the relationship between the diameter and the height of the conical pile?

    -The diameter of the base of the cone is always five times the height of the pile.

  • How is the volume of a cone calculated?

    -The volume of a cone is calculated using the formula 1/3 * pi * r^2 * h, where r is the radius of the base and h is the height of the cone.

  • What is the goal of the first problem in the script?

    -The goal of the first problem is to determine the rate at which the height of the conical pile is changing when the pile is 12 feet high.

  • How is the derivative of the volume of the cone with respect to time (dv/dt) related to the derivative of the height with respect to time (dh/dt)?

    -The derivative of the volume of the cone with respect to time is related to the derivative of the height with respect to time through the equation 50 = (25/12) * pi * (h^3) * (dh/dt).

  • What is the rate at which water is leaking out of the inverted conical tank?

    -The water is leaking out of the inverted conical tank at a rate of 7,500 cubic centimeters per minute.

  • What is the height and diameter of the conical tank when the water level is falling at a rate of 15 centimeters per minute?

    -When the water level is falling at a rate of 15 centimeters per minute, the height of the water in the tank is 0.25 meters (or 25 centimeters), and the diameter at the top is 6 meters.

  • How can we find the rate at which water is flowing into the tank?

    -We can find the rate at which water is flowing into the tank by calculating the net volume flow rate, which is the difference between the rate of water flowing into the tank and the rate of water flowing out of the tank.

  • What is the final calculated rate at which water is flowing into the tank?

    -The final calculated rate at which water is flowing into the tank is 3,358 cubic centimeters per minute.

  • Why is the rate of water flowing into the tank positive?

    -The rate of water flowing into the tank is positive because this quantity represents the increase in the volume of water in the tank, whereas the leaking water decreases the volume.

  • How is the height of the cone related to the radius in the second problem?

    -In the second problem, the height of the cone is related to the radius by the ratio 8d = 6h, which leads to r being equal to 3h/8.

  • What units were used in the calculations for the second problem?

    -In the second problem, the units used were meters and centimeters, with the final answer being in cubic centimeters per minute.

Outlines
00:00
๐Ÿ“ˆ Calculating the Rate of Increase of a Conical Pile's Height

This paragraph discusses a related rates problem involving a conical pile formed by gravel falling off a conveyor belt at a rate of 50 cubic feet per minute. The base diameter of the cone is always five times the height of the pile. The goal is to determine the rate at which the height of the pile is increasing when the pile is 12 feet high. The solution involves understanding the volume of a cone, which is given by the formula (1/3)ฯ€r^2h, and differentiating this with respect to time to find the rate of change of height (dh/dt). The relationship between the diameter and height (d = 5h) is used to eliminate the radius variable, leading to the equation 50 = (25ฯ€/12)(dh/dt). Solving this, the rate of increase of the height is found to be 1/(18ฯ€) feet per minute.

05:01
๐Ÿ’ง Determining the Rate of Water Flow into a Leaky Conical Tank

The second paragraph presents a problem where water is leaking out of an inverted conical tank at a rate of 7,500 cubic centimeters per minute, and the tank has a height of eight meters with a top diameter of six meters. The water level is falling at a rate of 15 centimeters per minute when the height of the water is 0.25 meters. The task is to find the rate at which water is flowing into the tank. The solution requires understanding the net volume flow rate, which is the difference between the rate of water flowing into and out of the tank. The volume of the cone is given by (1/3)ฯ€r^2h, and by substituting the known values and solving the equation, the net rate of change of volume (dv/dt) is calculated. By adding the rate of water flowing out (7,500 cmยณ/min) to the net change in volume, the rate of water flowing into the tank (3,358 cmยณ/min) is determined.

Mindmap
Keywords
๐Ÿ’กrelated rates problem
A related rates problem is a type of mathematical challenge that involves solving for an unknown variable when two or more quantities are related by a constant ratio or function. In the video, the problem involves determining the rate of change of the height of a conical pile based on the rate of volume change and the relationship between the base diameter and height of the cone.
๐Ÿ’กconveyor belt
A conveyor belt is a machine used to transport materials, such as gravel or sand, from one place to another. In the context of the video, the conveyor belt is used to illustrate the continuous flow of material that forms a conical pile, which is key to understanding the related rates problem being discussed.
๐Ÿ’กcircular base
The circular base refers to the bottom, flat surface of a three-dimensional shape, such as a cone or a cylinder. In the video, the circular base is an essential part of the conical pile, and its diameter is related to the height of the cone, which is crucial for calculating the rate of change of the height.
๐Ÿ’กvolume
Volume is the measure of the amount of space occupied by an object. In the context of the video, the volume of the conical pile is calculated using the formula for the volume of a cone, which is vital for determining the rate at which the pile's height is changing.
๐Ÿ’กdifferentiation
Differentiation is a mathematical process that involves finding the rate of change of a function with respect to time or another variable. In the video, differentiation is used to find the rate at which the height of the conical pile is changing (dh/dt) based on the known rate of volume change.
๐Ÿ’กheight of the pile
The height of the pile refers to the vertical distance from the base to the apex of the conical pile. In the video, the height is a variable that the problem aims to find the rate of change for, given the conditions of the conveyor belt and the pile's geometry.
๐Ÿ’กdiameter
The diameter of a circle or circular base is the length of a straight line passing through the center of the circle. In the video, the diameter of the conical pile's base is given as a multiple of the height, which is essential for setting up the relationship needed to solve the related rates problem.
๐Ÿ’กradius
The radius is the distance from the center of a circle to any point on the circumference. In the context of the video, the radius is half of the diameter and is used in the formula for the volume of a cone and in the relationship with the height to solve the related rates problem.
๐Ÿ’กrate of change
The rate of change is a mathematical term that refers to the speed at which a quantity changes with respect to another quantity. In the video, the rate of change is central to solving for the unknown variable, which is the rate at which the height of the conical pile is increasing.
๐Ÿ’กcubic feet
Cubic feet is a unit of volume used to express the amount of space occupied by an object in three-dimensional space. In the video, the rate at which the volume of the conical pile changes is given in cubic feet per minute, which is essential for setting up and solving the related rates problem.
๐Ÿ’กinverted conical tank
An inverted conical tank is a container with a conical shape that has its apex at the bottom, resembling an ice cream cone upside down. In the video, the tank is used as an example to illustrate a different related rates problem involving water leaking out at a certain rate and the height of the water changing over time.
Highlights

Gravel falls off a conveyor belt onto a conical pile at a rate of 50 cubic feet per minute.

The diameter of the base of the cone is always five times the height of the pile.

The problem aims to determine how fast the height of the pile is increasing when the pile is 12 feet high.

The volume of a cone is represented by the equation 1/3 * pi * r^2 * h.

To find the rate of change of height (dh/dt), we relate the height to the volume with dv/dt = 50 cubic feet per minute.

The relationship between the radius (r) and height (h) is r = 5/2 * h.

Differentiating the volume equation with respect to time gives us the equation involving dr/dt and dh/dt.

The final calculation for the rate at which the height is changing (dh/dt) is 1/(18 * pi) feet per minute when the pile is 12 feet high.

The second problem involves water leaking out of an inverted conical tank at a rate of 7,500 cubic centimeters per minute.

The height of the tank is eight meters, and it has a diameter of six meters at the top.

The water level is falling at a rate of 15 centimeters per minute when the height of the water is 0.25 meters.

The goal is to find the rate at which water is flowing into the tank.

The net volume flow rate is the difference between the rate of water flowing into and out of the tank.

The volume of a cone is given by the equation 1/3 * pi * r^2 * h, which is used to calculate the net rate of volume change.

The relationship between the height (h) and radius (r) of the tank is r = 3h/8.

The derivative of the volume equation with respect to time (t) gives us the net dv/dt.

The net volume flow rate (dv/dt) is -4142 cubic centimeters per minute, indicating the rate at which the water level is decreasing.

To find the rate at which water is flowing into the tank (dv/dt), we add 7,500 cubic centimeters per minute to the net volume flow rate.

The final answer for the rate at which water is flowing into the tank is 3,358 cubic centimeters per minute, which is positive because it increases the volume of water.

Transcripts
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