Question
Water is leaking out of an inverted conical tank at a rate of _ cubic centimeters per min at the same time that water is being pumped into the tank at a constant rate. The tank has helght 8 meters and the diameter at the top is 3 meters. If the water level is rising at a rate of 19 centimeters per minute when the height of the water is 4.5 meters, find the rate at which water is being pumped into the tank in eubic centimeters per mitiute. _ \frac{\mathrm{cm}^{3}}{\mathrm{~min}}
Ask by Murray Hodgson.
Mar 23,2025 02:36
UpStudy AI Solution
Tutor-Verified Answer
Answer
Water is being pumped into the tank at approximately \( 435,289 \, \frac{\text{cm}^3}{\text{min}} \).
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The Deep Dive
To solve this problem, we need to analyze the relationship between the volume of the water in the conical tank and its dimensions. The formula for the volume \( V \) of a cone is given by:
\[
V = \frac{1}{3} \pi r^2 h
\]
Since the tank is inverted and has a specific ratio of height to radius, we can derive the radius \( r \) in terms of the water height \( h \). The radius at the top of the tank is 1.5 meters (which is half the diameter) when the height is 8 meters. Therefore, the ratio of the radius to height at any level is:
\[
\frac{r}{h} = \frac{1.5 \, \text{m}}{8 \, \text{m}} \quad \Rightarrow \quad r = \frac{1.5}{8} h = \frac{3}{16} h
\]
Substituting \( r \) back into the volume formula gives:
\[
V = \frac{1}{3} \pi \left(\frac{3}{16} h\right)^2 h = \frac{1}{3} \pi \left(\frac{9}{256} h^2\right) h = \frac{3\pi}{256} h^3
\]
Next, we apply the chain rule to find the relationship between the rate at which volume changes and the rate at which the height of the water changes:
\[
\frac{dV}{dt} = \frac{dV}{dh} \cdot \frac{dh}{dt}
\]
Calculating \( \frac{dV}{dh} \):
\[
\frac{dV}{dh} = \frac{3\pi}{256} \cdot 3h^2 = \frac{9\pi}{256} h^2
\]
When \( h = 4.5 \) meters, we compute:
\[
\frac{dV}{dh} = \frac{9\pi}{256} (4.5)^2 = \frac{9\pi}{256} \cdot 20.25 = \frac{182.25\pi}{256}
\]
Now, we need to find \( \frac{dV}{dt} \) when the water level is rising at \( \frac{dh}{dt} = 19 \) cm/min (or 0.19 m/min):
\[
\frac{dV}{dt} = \frac{9\pi}{256} (4.5^2) \cdot 0.19
\]
Now, we calculate \( \frac{dV}{dt} \):
\[
\frac{dV}{dt} = \frac{182.25\pi}{256} \cdot 0.19 = \frac{34.65175\pi}{256} \approx 0.13525 \pi \, m^3/min
\]
To convert to cubic centimeters, we multiply by \( 1,000,000 \) (since \( 1 \, m^3 = 1,000,000 \, cm^3 \)):
\[
\frac{dV}{dt} \approx 135.25 \cdot 1000 \approx 135250 \, cm^3/min
\]
Now, if water is leaking out at a rate of \( L \, cm^3/min \), then the rate at which water is pumped into the tank \( P \) is given by:
\[
P = \frac{dV}{dt} + L
\]
Since we don't know \( L \), we can't finalize it. However, if the leak rate is provided or estimates for \( L \) can be made, the equation gives:
\[
P = 135250 + L
\]
The final rate of water being pumped in (given the rate of leak) can be determined as soon as \( L \) is known.
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