Solving for Rate of Change in Sand Pile Height

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SUMMARY

The discussion focuses on calculating the rate of change of height in a conical sand pile, given a constant volume inflow of 10 cubic feet per minute. The volume formula used is V = (1/3)πr²h, where the radius r is related to the height h by the equation r = (1/3)h. The user encountered difficulties in deriving the correct expression for the rate of change of height (dh/dt) and questioned the application of the chain rule and product rule in their calculations. The correct approach requires careful differentiation, including the relationship between r and h.

PREREQUISITES
  • Understanding of calculus, specifically differentiation techniques.
  • Familiarity with the geometric properties of cones.
  • Knowledge of the chain rule and product rule in calculus.
  • Ability to manipulate algebraic expressions involving variables and constants.
NEXT STEPS
  • Review the application of the chain rule in related rates problems.
  • Study the geometric properties of conical shapes and their volume formulas.
  • Practice solving related rates problems involving different geometric solids.
  • Learn how to derive relationships between variables in multivariable calculus contexts.
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Students studying calculus, particularly those focusing on related rates problems, as well as educators looking for examples of applying differentiation to real-world scenarios.

lax1113
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Homework Statement


Sand is falling into a conical pile at a rate of 10 cubic feet/minute. The diameter of the cone is 3 times the altitude. At what rate is the height of the pile change when the height=15feet.


So i was going through and I don't know if i derived it wrong, but i had

v=1/3pi(r^2)h

so

dv/dt= pi/3 R^{2}(dh/dt) * 2pi/3 R (h)

but when i go through and solve it all with R= 3/2h I don't get the answer form the back of the book. Is my derivative wrong? I used chain rule...
 
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V(t)=(1/3)pi(r(t)^2)*h(t). If you do the derivative correctly, there ought to be a dr(t)/dt hanging around someplace. And why is there a '*' between the two parts of what looks like a product rule?
 

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