Chapter 22: Problem 12
heitsvektor \(\widehat{\boldsymbol{n}}=\frac{1}{\sqrt{6}}(1,-1,2)^{T}\) und zerlegen Sie den Vektor \(\boldsymbol{v}=(1,1,1)^{T}\) in zwei orthogonale Komponenten \(\boldsymbol{v}^{\prime}\) und \(\boldsymbol{v}^{\prime \prime}\), wobei \(\boldsymbol{v}^{\prime}\) zu \(\widehat{n}\) parallel ist.
Short Answer
Expert verified
Answer: The two orthogonal components of the vector (1,1,1) with respect to the unit normal vector (1/sqrt(6), -1/sqrt(6), 2/sqrt(6)) are:
1) The parallel component: (1/3, -1/3, 2/3)
2) The orthogonal component: (2/3, 4/3, 1/3)
Step by step solution
01
Find the parallel component
To find the component of \(\boldsymbol{v}\) parallel to \(\widehat{\boldsymbol{n}}\), we can use the projection formula:
\(\boldsymbol{v}^{\prime} = (\boldsymbol{v} \cdot \widehat{\boldsymbol{n}}) \widehat{\boldsymbol{n}}\)
First, calculate the dot product of \(\boldsymbol{v}\) and \(\widehat{\boldsymbol{n}}\):
\(\boldsymbol{v} \cdot \widehat{\boldsymbol{n}} = (1,1,1) \cdot \frac{1}{\sqrt{6}}(1,-1,2) = \frac{1}{\sqrt{6}}(1 - 1 + 2) = \frac{2}{\sqrt{6}}\)
Now, multiply this result by \(\widehat{\boldsymbol{n}}\) to get the parallel component:
\(\boldsymbol{v}^{\prime} = \frac{2}{\sqrt{6}}\frac{1}{\sqrt{6}}(1,-1,2)^{T} = \frac{1}{3}(1,-1,2)^{T}\)
02
Find the orthogonal component
To find the component of \(\boldsymbol{v}\) orthogonal to \(\widehat{\boldsymbol{n}}\), we can subtract the parallel component \(\boldsymbol{v}^{\prime}\) from the original vector \(\boldsymbol{v}\):
\(\boldsymbol{v}^{\prime\prime} = \boldsymbol{v} - \boldsymbol{v}^{\prime} = (1,1,1)^{T} - \frac{1}{3}(1,-1,2)^{T}\)
Calculate the difference to get the orthogonal component:
\(\boldsymbol{v}^{\prime\prime} = \left(1 - \frac{1}{3}, 1 + \frac{1}{3}, 1 - \frac{2}{3}\right)^{T} = \left(\frac{2}{3}, \frac{4}{3}, \frac{1}{3}\right)^{T}\)
03
Verify the orthogonality and parallelism
To make sure our solution is correct, we need to verify that \(\boldsymbol{v}^{\prime}\) is parallel to \(\widehat{\boldsymbol{n}}\), and that \(\boldsymbol{v}^{\prime}\) and \(\boldsymbol{v}^{\prime\prime}\) are orthogonal to each other.
First, check the parallelism. We found \(\boldsymbol{v}^{\prime} = \frac{1}{3}(1,-1,2)^{T}\). Since this is just a scalar multiple of \(\widehat{\boldsymbol{n}}\), they are parallel.
Next, check the orthogonality by finding the dot product of \(\boldsymbol{v}^{\prime}\) and \(\boldsymbol{v}^{\prime\prime}\):
\(\boldsymbol{v}^{\prime} \cdot \boldsymbol{v}^{\prime\prime} = \left(\frac{1}{3}, -\frac{1}{3}, \frac{2}{3}\right) \cdot \left(\frac{2}{3}, \frac{4}{3}, \frac{1}{3}\right) = \frac{1}{9}(2 - 4 + 2) = 0\)
Since their dot product is 0, \(\boldsymbol{v}^{\prime}\) and \(\boldsymbol{v}^{\prime\prime}\) are orthogonal. Thus, we have successfully decomposed the vector \(\boldsymbol{v}\) into two orthogonal components:
\(\boldsymbol{v}^{\prime} = \frac{1}{3}(1,-1,2)^{T}\) (parallel to \(\widehat{\boldsymbol{n}}\))
\(\boldsymbol{v}^{\prime\prime} = \left(\frac{2}{3}, \frac{4}{3}, \frac{1}{3}\right)^{T}\) (orthogonal to \(\widehat{\boldsymbol{n}}\))
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Orthogonal Components
When discussing vectors, "orthogonal components" refer to parts of a vector that are perpendicular to each other. This concept comes into play when we break down a vector into specific sections that are related to another vector, like the process of decomposing the vector \( \boldsymbol{v} \) into \( \boldsymbol{v}^{\prime} \) and \( \boldsymbol{v}^{\prime\prime} \). Here, \( \boldsymbol{v} = (1,1,1)^T \) is split into two parts:
- \( \boldsymbol{v}^{\prime} \) which is parallel to the reference direction given by \( \widehat{\boldsymbol{n}} \).
- \( \boldsymbol{v}^{\prime\prime} \) which is orthogonal (or perpendicular) to \( \widehat{\boldsymbol{n}} \).
Projection Formula
The 'projection formula' is a key tool in vector decomposition used to find the component of one vector along the direction of another. In our example, to determine \( \boldsymbol{v}^{\prime} \) (the parallel component), we use the formula:
\[ \boldsymbol{v}^{\prime} = (\boldsymbol{v} \cdot \widehat{\boldsymbol{n}}) \widehat{\boldsymbol{n}} \]
This formula tells us to first find the dot product of \( \boldsymbol{v} \) and \( \widehat{\boldsymbol{n}} \). This numerical result represents how much of \( \boldsymbol{v} \) aligns with \( \widehat{\boldsymbol{n}} \).
\[ \boldsymbol{v}^{\prime} = (\boldsymbol{v} \cdot \widehat{\boldsymbol{n}}) \widehat{\boldsymbol{n}} \]
This formula tells us to first find the dot product of \( \boldsymbol{v} \) and \( \widehat{\boldsymbol{n}} \). This numerical result represents how much of \( \boldsymbol{v} \) aligns with \( \widehat{\boldsymbol{n}} \).
- Multiply this scalar with the unit direction vector \( \widehat{\boldsymbol{n}} \) to gain the exact directional component \( \boldsymbol{v}^{\prime} \).
Parallel and Orthogonal Vectors
In vector algebra, two vectors are parallel if they point in the same or exactly opposite directions. This is checked if one vector is a scalar multiple of the other. In our case, \( \boldsymbol{v}^{\prime} = \frac{1}{3}(1,-1,2)^T \) is a scalar multiple of \( \widehat{\boldsymbol{n}} \), confirming that these vectors are parallel.
On the contrary, vectors are orthogonal if their dot product equals zero. When solving our exercise, we confirmed that \( \boldsymbol{v}^{\prime} \) and \( \boldsymbol{v}^{\prime\prime} \) are orthogonal by calculating:\[ \boldsymbol{v}^{\prime} \cdot \boldsymbol{v}^{\prime\prime} = 0 \]
This calculation ensures that the vectors are indeed perpendicular to each other, a crucial property when resolving a vector into components.
On the contrary, vectors are orthogonal if their dot product equals zero. When solving our exercise, we confirmed that \( \boldsymbol{v}^{\prime} \) and \( \boldsymbol{v}^{\prime\prime} \) are orthogonal by calculating:\[ \boldsymbol{v}^{\prime} \cdot \boldsymbol{v}^{\prime\prime} = 0 \]
This calculation ensures that the vectors are indeed perpendicular to each other, a crucial property when resolving a vector into components.
Dot Product Calculation
The 'dot product' is a fundamental operation in vector mathematics that gives a scalar value. It serves multiple purposes, such as determining the angle between vectors or projecting one vector onto another. In our exercise, the calculation \( \boldsymbol{v} \cdot \widehat{\boldsymbol{n}} \) was essential. This yielded:
\[ \boldsymbol{v} \cdot \widehat{\boldsymbol{n}} = \frac{2}{\sqrt{6}} \]
Why is this important? Because it indicates how much of \( \boldsymbol{v} \) lies in the direction of \( \widehat{\boldsymbol{n}} \). The result is used in the projection formula to find \( \boldsymbol{v}^{\prime} \). This dot product also enables us to verify the orthogonality between \( \boldsymbol{v}^{\prime} \) and \( \boldsymbol{v}^{\prime\prime} \), illustrating the broad application of this operation in vector analysis.
\[ \boldsymbol{v} \cdot \widehat{\boldsymbol{n}} = \frac{2}{\sqrt{6}} \]
Why is this important? Because it indicates how much of \( \boldsymbol{v} \) lies in the direction of \( \widehat{\boldsymbol{n}} \). The result is used in the projection formula to find \( \boldsymbol{v}^{\prime} \). This dot product also enables us to verify the orthogonality between \( \boldsymbol{v}^{\prime} \) and \( \boldsymbol{v}^{\prime\prime} \), illustrating the broad application of this operation in vector analysis.