Math Problem Statement

A conical​ container, oriented such that its vertex is at the​ bottom, has radius 9 ft and height 36 ft. It is filled to a height of 33 ft of a liquid weighing 51.8 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 solve this, we'll use calculus to compute the work required to pump the liquid to the rim of the cone.

Step 1: Define the Work Integral

The general formula for work required to lift a volume of liquid is:

dW=(weight density)×(volume slice)×(lifting distance)dW = \text{(weight density)} \times \text{(volume slice)} \times \text{(lifting distance)}

The total work is obtained by integrating over the height of the liquid.

W=ab(weight density)×(cross-sectional area)×(lifting distance)dyW = \int_{a}^{b} \text{(weight density)} \times \text{(cross-sectional area)} \times \text{(lifting distance)} \, dy

where:

  • The weight density of the liquid is 51.851.8 lb/ft³.
  • The radius of the conical tank is 99 ft, and the height is 3636 ft.
  • The liquid is filled up to a height of 3333 ft.
  • The volume of a thin slice at height yy is given by the area of the cross-section times the thickness dydy.
  • The lifting distance for a slice at height yy is 36y36 - y (since the rim is at y=36y = 36).

Step 2: Express the Radius as a Function of Height

The cone follows a linear relation between its height and radius. The equation of the cone's radius at any height yy can be determined using similar triangles:

r=936y=y4r = \frac{9}{36} y = \frac{y}{4}

Thus, the cross-sectional area (circle) at height yy is:

A(y)=πr2=π(y4)2=πy216A(y) = \pi r^2 = \pi \left(\frac{y}{4}\right)^2 = \frac{\pi y^2}{16}

Step 3: Set Up the Integral

The volume of a thin slice is:

dV=A(y)dy=πy216dydV = A(y) dy = \frac{\pi y^2}{16} dy

The weight of the slice is:

Weight=51.8×dV=51.8×πy216dy\text{Weight} = 51.8 \times dV = 51.8 \times \frac{\pi y^2}{16} dy

The work to lift this slice to the top is:

dW=51.8×πy216(36y)dydW = 51.8 \times \frac{\pi y^2}{16} (36 - y) dy

Thus, the total work integral is:

W=03351.8×πy216(36y)dyW = \int_{0}^{33} 51.8 \times \frac{\pi y^2}{16} (36 - y) dy

Let's compute this integral. sympy as sp

Define variables

y = sp.Symbol('y')

Given constants

density = 51.8 # lb/ft³ radius_ratio = 1/4 # r = y/4 pi = sp.pi

Cross-sectional area

A_y = pi * (y/4)**2

Weight of a thin slice

dV = A_y weight = density * dV

Lifting distance

lifting_distance = 36 - y

Work integral

W_integral = weight * lifting_distance

Compute the integral from y = 0 to y = 33

W_total = sp.integrate(W_integral, (y, 0, 33))

Evaluate the result numerically

W_total_value = W_total.evalf()

W_total_valueThe amount of work required to pump the liquid to the rim of the tank is 1,370,669 ft-lb (rounded to the nearest whole number).

Would you like a detailed breakdown of the calculations or explanation of any step?

Related Questions:

  1. How would the work change if the liquid had a different weight density?
  2. What if the cone were only partially filled, say to a height of 20 ft?
  3. How does the work compare if the cone were upside down?
  4. How much work would it take to pump the entire cone full of liquid?
  5. How would the integral setup change if the liquid were pumped to a higher level?

Tip:

When solving work problems in physics and calculus, always check if similar triangles can be used to simplify the radius or cross-sectional area formula.

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Math Problem Analysis

Mathematical Concepts

Calculus
Work in Physics
Integration
Similar Triangles

Formulas

Work Integral: W = ∫ (weight density) × (cross-sectional area) × (lifting distance) dy
Volume of a thin slice: dV = A(y) dy
Cross-sectional area of a cone: A(y) = π (y/4)^2
Weight of a slice: weight = 51.8 × (π y² / 16) dy
Lifting distance: 36 - y

Theorems

Fundamental Theorem of Calculus
Volume by Slicing

Suitable Grade Level

Undergraduate Calculus or Advanced High School (AP Calculus)