Math Problem Statement
It is given that a container is in the form of an inverted right circular cone with a base radius 4 cm and height 16 cm. The container is held vertically. Initially, the container is fully filled with water. Then the water pumped out from the container at a constant rate of 60 cm3/s. Let V cm3 and h cm can be the volume and the depth of water in the container respectively after t seconds.
Solution
Let's break this problem down and set up the relations we need to solve it.
Step 1: Volume of a cone
The container is in the shape of an inverted right circular cone. The volume of a cone is given by the formula: where:
- is the radius of the base of the cone,
- is the height (or depth in this context),
- is the mathematical constant Pi (approximately 3.1416).
However, the radius of the water level decreases as the water level drops. Since the cone is similar to the full cone, the radius of the water surface at any depth is proportional to the depth . For the full cone, when cm, cm. Therefore, we can express the radius as a function of using the proportionality: Thus, at any depth , the radius of the water is:
Step 2: Volume as a function of depth
Now substitute this expression for into the formula for the volume: This simplifies to: This gives the volume of water in the container as a function of the depth .
Step 3: Rate of change of volume
The water is being pumped out at a constant rate of 60 cm³/s. This means that the volume is decreasing over time at a rate of: We can use the chain rule to relate the rate of change of volume to the rate of change of depth :
First, find by differentiating the volume function :
Now, substitute into the chain rule: Solving for , we get: This gives the rate of change of the water depth with respect to time .
Step 4: Initial conditions and further analysis
- At , the container is fully filled, meaning .
- The relationship between volume, depth, and time could be further analyzed by integrating the rate of change of with respect to time.
Let me know if you'd like to explore more detailed steps in solving for or specific questions about this setup!
Follow-up questions:
- How long does it take to completely empty the container?
- What is the depth of the water after 30 seconds?
- How does the rate at which the depth decreases change as the water level drops?
- How would the problem change if the cone had a different base radius or height?
- Could we solve for the time when the water depth reaches a specific value (e.g., 8 cm)?
Tip:
When working with related rates, always express all quantities in terms of a single variable before differentiating to avoid errors.
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Math Problem Analysis
Mathematical Concepts
Geometry (Volume of a Cone)
Calculus (Rate of Change, Related Rates)
Proportionality
Formulas
V = (1/3)πr²h (Volume of a cone)
r/h = 1/4 (Proportional relationship)
V(h) = (πh³)/48 (Volume of water as a function of depth)
dV/dt = -60 cm³/s (Rate of change of volume)
Theorems
Chain Rule (for relating rates)
Derivative of Power Rule (d/dh of h³)
Suitable Grade Level
Grades 11-12
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