Rate of Water Rise in Cone-Shaped Vessel

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Discussion Overview

The discussion revolves around determining the rate of water rise in a cone-shaped vessel as it fills with water at a steady rate of 1m³ per minute. The focus includes the relationship between the dimensions of the cone of water and the vessel's geometry, as well as the mathematical differentiation required to find the rate of height increase when the vessel is 1/8 full.

Discussion Character

  • Mathematical reasoning
  • Technical explanation
  • Exploratory

Main Points Raised

  • One participant presents the volume formula for a cone, v = (1/3)πr²h, and expresses difficulty in differentiating it.
  • Another participant questions how the radius and height of the water cone are related over time.
  • A participant suggests that both the radius and height increase as the water fills the vessel.
  • It is noted that the radius of the vessel is half its height, leading to the conclusion that the cone of water will maintain a similar shape to the vessel, allowing for the relationship r = (1/2)h to be established.
  • Participants discuss expressing the volume of water as a function of height alone and imply that implicit differentiation with respect to time could be used to find the rate of height increase.
  • There is a mention of needing to know the height of the water when the vessel is 1/8 full, which is suggested to be half the height of the vessel based on similarity arguments.

Areas of Agreement / Disagreement

Participants appear to agree on the geometric relationship between the dimensions of the cone of water and the vessel. However, there is no consensus on the differentiation process or the specific calculations needed to find the rate of height increase.

Contextual Notes

There are limitations regarding the assumptions made about the similarity of the cone shapes and the need for clarity on the differentiation steps involved in the calculations.

markosheehan
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a vessel in the shape of a cone is standing on its apex. water flows in at a steady rate, of 1m^3 per minute. the vessel has a height of 2m and a diameter of 2m when the vessel is 1/8 full find the rate at which water is rising

v=1/3 pi r^2 h however i can't differentiate this
 
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At any point in time, how are the radius and height of the "cone of water" within the conical vessel related?
 
I don't know but I know they both get bigger with time.
 
markosheehan said:
I don't know but I know they both get bigger with time.

The vessel into which the water is flowing has a radius that is one half the height. Any "cone of water" partially or completely filling the vessel will be similar in shape to the vessel itself...so we may state (for the conical volume of water):

$$r=\frac{1}{2}h$$

And now, you can express the volume of water as a function of $h$ alone...and then implicitly differentiate with respect to time $t$ and given that you know $$\d{V}{t}$$, you may solve for $$\d{h}{t}$$

You will also need to know the height of the volume of water when the vessel is 1/8 full. By similarity, we see this is when the height of the water is 1/2 that of the vessel. ;)
 

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