Math Problem Statement

Question content area top Part 1 A conical​ container, oriented such that its vertex is at the​ bottom, has radius 8 ft and height 32 ft. It is filled to a height of 29 ft of a liquid weighing 64.4 lb divided by ft cubed. How much work will it take to pump the contents to the​ rim? How much work will it take to pump the liquid to a level of 3 ft above the​ cone's rim? Question content area bottom Part 1 The amount of work required to pump the liquid to the rim of the tank is    enter your response here ​ft-lb. ​(Round to the nearest whole number as​ needed.)

Solution

To calculate the amount of work required to pump the liquid from a conical tank, we can break down the task into smaller steps. The formula for work in this context is:

W=abF(x)dxW = \int_{a}^{b} F(x) \, dx

Where F(x)F(x) is the force needed to lift a thin slice of liquid at a height xx, and [a,b][a, b] represents the bounds of integration (the range over which the liquid is lifted).

Step 1: Setting up the Problem

The cone has a height of 32 ft, and it is filled with liquid up to a height of 29 ft. The liquid has a weight density of 64.4 lb/ft³.

Key Details:

  • Radius of cone = 8 ft
  • Height of cone = 32 ft
  • Liquid is filled to a height of 29 ft
  • Weight density = 64.4 lb/ft³

We want to calculate how much work is needed to pump the liquid from a height of 29 ft to the rim of the cone, which is at 32 ft.

Step 2: Understanding the Geometry of the Cone

For a cone, the radius at any height hh is proportional to hh. The radius at height hh can be given by:

r(h)=832×h=h4r(h) = \frac{8}{32} \times h = \frac{h}{4}

Thus, the radius of the liquid at a height hh (where hh ranges from 0 to 29 ft) will be h4\frac{h}{4}.

Step 3: Calculating the Work

Work is the force required to lift a thin layer of liquid over the distance it needs to be pumped. We can calculate the volume of a thin slice of liquid at height hh (with thickness dhdh) and then determine the force required to lift that slice.

The volume dVdV of a thin slice of liquid at height hh is the volume of a disk, which is:

dV=πr2dh=π(h4)2dh=πh216dhdV = \pi r^2 dh = \pi \left(\frac{h}{4}\right)^2 dh = \frac{\pi h^2}{16} dh

The weight of this slice is given by:

dW=Weight density×dV=64.4×πh216dh=64.4πh216dhdW = \text{Weight density} \times dV = 64.4 \times \frac{\pi h^2}{16} dh = \frac{64.4 \pi h^2}{16} dh

To find the total work, we need to multiply the weight of the slice by the distance it has to be lifted. The liquid is being pumped from height hh to the top of the cone, which is at 32 ft. Therefore, the distance to lift the slice is 32h32 - h.

The work to lift a thin slice is:

dW=(64.4πh216)×(32h)dhdW = \left( \frac{64.4 \pi h^2}{16} \right) \times (32 - h) dh

Now, integrate this expression from h=3h = 3 ft (since the liquid is filled to a height of 29 ft) to h=29h = 29 ft to find the total work:

W=32964.4πh2(32h)16dhW = \int_3^{29} \frac{64.4 \pi h^2 (32 - h)}{16} dh

Step 4: Solving the Integral

Let's calculate the work step by step:

  1. Simplify the expression:

W=64.4π16329h2(32h)dhW = \frac{64.4 \pi}{16} \int_3^{29} h^2 (32 - h) dh

  1. Distribute h2h^2 inside the parentheses:

W=64.4π16329(32h2h3)dhW = \frac{64.4 \pi}{16} \int_3^{29} (32h^2 - h^3) dh

  1. Integrate each term separately:

32h2dh=32h33,h3dh=h44\int 32h^2 dh = \frac{32h^3}{3}, \quad \int h^3 dh = \frac{h^4}{4}

Thus,

W=64.4π16[32h33h44]329W = \frac{64.4 \pi}{16} \left[ \frac{32h^3}{3} - \frac{h^4}{4} \right]_3^{29}

  1. Evaluate the integral at h=29h = 29 and h=3h = 3:

W=64.4π16((32(29)33(29)44)(32(3)33(3)44))W = \frac{64.4 \pi}{16} \left( \left( \frac{32(29)^3}{3} - \frac{(29)^4}{4} \right) - \left( \frac{32(3)^3}{3} - \frac{(3)^4}{4} \right) \right)

You can compute the exact value using a calculator or further simplify. After evaluating this expression, you will find the total work required to pump the liquid to the rim of the cone.

Let me know if you'd like help with the exact numerical evaluation or any further breakdown of steps!

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Math Problem Analysis

Mathematical Concepts

Calculus
Work Calculation
Integration
Geometry of Cones

Formulas

Work formula: W = ∫(a to b) F(x) dx
Radius of cone at height h: r(h) = h/4
Volume of a thin slice: dV = π (r(h))² dh
Weight of a thin slice: dW = 64.4 × π (h²/16) dh
Work to pump a thin slice: dW = (64.4πh²/16) × (32 - h) dh

Theorems

Fundamental Theorem of Calculus
Principle of Work and Force

Suitable Grade Level

College-level Calculus (Undergraduate)