Math Problem Statement

find the total work done in moving a parcticle in a force field given by F = 3x * y deg - 52 deg + 10xk along the x = 1 + t ^ 2 y = 24 ^ 2 z = f ^ 3 from 1/x = 1 + f = 2

Solution

To find the total work done in moving a particle in a given force field along a specified path, we need to use the line integral of the force field along the path.

Given: F=3xi+yj+10xk\mathbf{F} = 3x \mathbf{i} + y \mathbf{j} + 10x \mathbf{k} where i\mathbf{i}, j\mathbf{j}, and k\mathbf{k} are the unit vectors along the xx-, yy-, and zz-axes, respectively.

The path is defined by the parametric equations: x=1+t2,y=242,z=t3x = 1 + t^2, \quad y = 24^2, \quad z = t^3 where tt is the parameter that varies.

The limits for tt are derived from the condition 1x=1+t=2\frac{1}{x} = 1 + t = 2. We need to solve this equation to find the limits of tt.

Step 1: Determine the Limits of Integration

From the equation 1x=2\frac{1}{x} = 2, solve for xx:

x=12x = \frac{1}{2} But from the parametric equation x=1+t2x = 1 + t^2, set this equal to 12\frac{1}{2}:

1+t2=121 + t^2 = \frac{1}{2}

This equation has no real solution since t20t^2 \geq 0, and 1+t21 + t^2 is always greater than or equal to 1. This suggests there's an issue with the setup or conditions of the problem. Let's address this.

Clarification and Redefinition

Let's assume instead that the path is simply defined for a certain range of tt. We would then define the work done as the integral over this range, and you'd specify this range separately.

Assuming tt varies from t=0t = 0 to t=1t = 1 as an example, we compute the line integral.

Step 2: Parametrize the Force Field

Substitute the parametric equations into the force field:

F(t)=3(1+t2)i+(242)j+10(1+t2)k\mathbf{F}(t) = 3(1 + t^2) \mathbf{i} + (24^2) \mathbf{j} + 10(1 + t^2) \mathbf{k}

Step 3: Calculate the Work Done

The work done WW is given by: W=CFdrW = \int_{C} \mathbf{F} \cdot d\mathbf{r} where drd\mathbf{r} is the differential displacement vector along the curve.

Substitute r(t)=(1+t2)i+242j+t3k\mathbf{r}(t) = (1 + t^2) \mathbf{i} + 24^2 \mathbf{j} + t^3 \mathbf{k}.

The derivative dr/dtd\mathbf{r}/dt gives: drdt=2ti+0j+3t2k\frac{d\mathbf{r}}{dt} = 2t \mathbf{i} + 0 \mathbf{j} + 3t^2 \mathbf{k}

So, the dot product F(t)drdt\mathbf{F}(t) \cdot \frac{d\mathbf{r}}{dt} is: [ \mathbf{F}(t) \cdot \frac{d\mathbf{r}}{dt} = \left[ 3(1 + t^2) \right] \cdot 2t + \left[ 24^2 \right] \cdot 0 + \left[ 10(1 + t^2) \right] \cdot 3t^2 ]

Simplifying: W=01[6t(1+t2)+30t2(1+t2)]dtW = \int_{0}^{1} \left[ 6t(1 + t^2) + 30t^2(1 + t^2) \right] dt

Expand and combine like terms: W=01[6t+6t3+30t2+30t4]dtW = \int_{0}^{1} \left[ 6t + 6t^3 + 30t^2 + 30t^4 \right] dt

Step 4: Evaluate the Integral

Evaluate each term separately: W=[3t2+6t44+10t3+30t55]01W = \left[ 3t^2 + \frac{6t^4}{4} + 10t^3 + \frac{30t^5}{5} \right]_{0}^{1}

Substituting the limits: W=[3(1)2+6(1)44+10(1)3+30(1)55]0W = \left[ 3(1)^2 + \frac{6(1)^4}{4} + 10(1)^3 + \frac{30(1)^5}{5} \right] - 0

This simplifies to: W=3+1.5+10+6=20.5 units of workW = 3 + 1.5 + 10 + 6 = 20.5 \text{ units of work}

So, the total work done is 20.5 units.

Additional Questions

  1. What would happen if we changed the path in the integral to another form?
  2. How does the force field affect the work done if the path changes direction?
  3. How can we generalize this to three-dimensional curves?
  4. What if the force field is not conservative? How would this affect the calculation?
  5. How does the choice of parameter tt affect the integral?

Tip: When dealing with line integrals, always verify the parameter limits and the curve's definition to avoid contradictions.

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Math Problem Analysis

Mathematical Concepts

Line Integrals
Parametric Equations
Vector Fields

Formulas

Work done by a force field: W = \int_{C} \mathbf{F} \cdot d\mathbf{r}

Theorems

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Suitable Grade Level

College Level