Math Problem Statement

Consider a thin rod oriented along the x-axis over the interval [5,11]. If the density of the rod is given by p(x)=4x^2 + 2, what is the mass of the rod? (If necessary, round to four decimal places.)

Solution

To find the mass of the rod, we integrate the density function p(x)p(x) over the given interval. The formula for the mass of a thin rod is:

M=abp(x)dxM = \int_{a}^{b} p(x) \, dx

where p(x)p(x) is the density function and [a,b][a, b] is the interval along the x-axis.

In this case:

  • p(x)=4x2+2p(x) = 4x^2 + 2
  • The rod extends over the interval [5,11][5, 11]

So, the mass MM is:

M=511(4x2+2)dxM = \int_{5}^{11} (4x^2 + 2) \, dx

Let's compute this integral step by step:

  1. Break down the integral: M=5114x2dx+5112dxM = \int_{5}^{11} 4x^2 \, dx + \int_{5}^{11} 2 \, dx

  2. Compute the integrals:

    • 4x2dx=43x3\int 4x^2 \, dx = \frac{4}{3}x^3
    • 2dx=2x\int 2 \, dx = 2x

Now, apply the limits of integration.

For 5114x2dx\int_{5}^{11} 4x^2 \, dx: [43x3]511=43(113)43(53)\left[\frac{4}{3}x^3\right]_{5}^{11} = \frac{4}{3}(11^3) - \frac{4}{3}(5^3)

For 5112dx\int_{5}^{11} 2 \, dx: [2x]511=2(11)2(5)\left[2x\right]_{5}^{11} = 2(11) - 2(5)

Let's calculate the exact value.The mass of the rod is 1620.00001620.0000 units.

Would you like more details or have any questions about the process?

Here are five related questions to deepen your understanding:

  1. How does the mass change if the interval is expanded to [4,12][4, 12]?
  2. What happens if the density function is a linear function instead of quadratic?
  3. Can you derive the center of mass for the rod based on this density function?
  4. How would the result change if the density was p(x)=4x3+2p(x) = 4x^3 + 2 instead?
  5. What are the physical interpretations of each term in the density function?

Tip: When integrating polynomial functions, split the integral into simpler components for easier calculations.

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Math Problem Analysis

Mathematical Concepts

Integral Calculus
Density Functions
Polynomials

Formulas

Mass of rod M = ∫(a to b) p(x) dx
∫ x^n dx = (x^(n+1))/(n+1) + C

Theorems

Fundamental Theorem of Calculus

Suitable Grade Level

Grades 11-12 (Advanced High School Calculus)