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If \(\vec{B}\) is added to \(\vec{A}\), the result is \(6.0 \hat{\mathrm{i}}+1.0 \hat{\mathrm{j}}\). If \(\vec{B}\) is subtracted from \(\vec{A}\), the result is \(-4.0 \hat{\mathrm{i}}+7.0 \hat{\mathrm{j}}\). What is the magnitude of \(\vec{A} ?\)

Short Answer

Expert verified
The magnitude of \(\vec{A}\) is approximately 4.12.

Step by step solution

01

Set Up Equations for Vector Addition and Subtraction

Start by writing down the two given equations based on vector addition and subtraction.1. When \(\vec{B}\) is added to \(\vec{A}\): \[\vec{A} + \vec{B} = 6.0 \hat{\mathrm{i}} + 1.0 \hat{\mathrm{j}}\]2. When \(\vec{B}\) is subtracted from \(\vec{A}\): \[\vec{A} - \vec{B} = -4.0 \hat{\mathrm{i}} + 7.0 \hat{\mathrm{j}}\]
02

Solve for Components of \(\vec{A}\)

Add the two equations to eliminate \(\vec{B}\) and solve for the components of \(\vec{A}\).\[\begin{align*}\vec{A} + \vec{B} &= 6.0 \hat{\mathrm{i}} + 1.0 \hat{\mathrm{j}} \ \vec{A} - \vec{B} &= -4.0 \hat{\mathrm{i}} + 7.0 \hat{\mathrm{j}} \ \hline 2\vec{A} &= 2.0 \hat{\mathrm{i}} + 8.0 \hat{\mathrm{j}} \end{align*}\]This simplifies to \(\vec{A} = 1.0 \hat{\mathrm{i}} + 4.0 \hat{\mathrm{j}}\).
03

Calculate the Magnitude of \(\vec{A}\)

Use the components of \(\vec{A}\) that we found in Step 2 to determine the magnitude.The magnitude is given by the formula \(|\vec{A}| = \sqrt{(A_x)^2 + (A_y)^2}\).Substitute \(A_x = 1.0\) and \(A_y = 4.0\):\[\begin{align*}|\vec{A}| &= \sqrt{(1.0)^2 + (4.0)^2} \ &= \sqrt{1.0 + 16.0} \ &= \sqrt{17.0} ≈ 4.12\end{align*}\]

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Vector Addition
Vector addition is a fundamental concept in mathematics and physics, representing the process of combining two or more vectors to form a resultant vector. In our exercise, when vector \( \vec{B} \) is added to vector \( \vec{A} \), the resultant vector is given by \( 6.0 \hat{\mathrm{i}} + 1.0 \hat{\mathrm{j}} \). Understanding vector addition involves several key points:
  • The addition of vectors is commutative, meaning \( \vec{A} + \vec{B} = \vec{B} + \vec{A} \).
  • Adding vectors involves summing their corresponding components. For example, the \( i \)-components and \( j \)-components are each summed independently.
  • The resultant vector gives a new direction and magnitude, derived from the combination of the original vectors.
In our step-by-step solution, vector addition is used to combine \( \vec{A} + \vec{B} \) which results in \( 6.0 \hat{\mathrm{i}} + 1.0 \hat{\mathrm{j}} \). This is a straightforward application of adding the \( i \) and \( j \) components separately. Understanding how to visually add vectors can help as well. You can think of vectors as arrows showing direction and magnitude, placing them tail-to-head to find the resultant vector easily.
Vector Subtraction
Vector subtraction is another crucial concept, which modifies the direction of the vector being subtracted. For instance, subtracting\( \vec{B} \) from \( \vec{A} \) effectively means adding \(-\vec{B}\) (the negation of \( \vec{B} \)) to \( \vec{A} \). In our problem, this operation gives the result \(-4.0 \hat{\mathrm{i}} + 7.0 \hat{\mathrm{j}} \).When performing vector subtraction, keep in mind:
  • Vector subtraction is not commutative, which means \( \vec{A} - \vec{B} eq \vec{B} - \vec{A} \).
  • Vector subtraction is akin to vector addition of a negative vector. This involves flipping the direction of the vector that is being subtracted.
  • Like addition, subtraction involves dealing with corresponding components separately, i.e., \(i\) and \(j\) components.
To solve the exercise, the equations \( \vec{A} + \vec{B} = 6.0 \hat{\mathrm{i}} + 1.0 \hat{\mathrm{j}} \) and \( \vec{A} - \vec{B} = -4.0 \hat{\mathrm{i}} + 7.0 \hat{\mathrm{j}} \) were used together. Solving these equations allows us to find the original vector components of \( \vec{A} \). Understanding vector subtraction well is crucial for solving such exercises easily.
Vector Components
Vectors in two dimensions can be broken down into their components, which simplify calculations involving them. These components are typically aligned along the Cartesian coordinate axes, such as \( \hat{\mathrm{i}} \) and \( \hat{\mathrm{j}} \) for the \( x \) and \( y \) axes respectively.Here are a few important facts about vector components:
  • Each vector can be represented as the sum of its components, such as \( \vec{A} = A_x \hat{\mathrm{i}} + A_y \hat{\mathrm{j}} \).
  • Components are scalar values which can be added, subtracted, or subjected to other mathematical operations independently.
  • When solving vector equations, determining the components often leads to solving a system of equations to find unknown quantities.
In our problem, once the components of \( \vec{A} \) were isolated following both addition and subtraction of \( \vec{B} \), we established that \( \vec{A} = 1.0 \hat{\mathrm{i}} + 4.0 \hat{\mathrm{j}} \). Using these components, we calculated the magnitude of vector \( \vec{A} \) via the formula \( |\vec{A}| = \sqrt{(A_x)^2 + (A_y)^2} \). Understanding vector components is instrumental in converting practical vector problems into manageable mathematical scenarios.

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Most popular questions from this chapter

A vector \(\vec{a}\) of magnitude 10 units and another vector \(\vec{b}\) of magnitude \(6.0\) units differ in directions by \(60^{\circ} .\) Find (a) the scalar product of the two vectors and (b) the magnitude of the vector product \(\vec{a} \times \vec{b}\)

Displacement \(\vec{d}_{1}\) is in the \(y z\) plane \(63.0^{\circ}\) from the positive direction of the \(y\) axis, has a positive \(z\) component, and has a magnitude of \(4.50 \mathrm{~m} .\) Displacement \(\vec{d}_{2}\) is in the \(x z\) plane \(30.0^{\circ}\) from the positive direction of the \(x\) axis, has a positive \(z\) component, and has magnitude \(1.40 \mathrm{~m}\). What are (a) \(\vec{d}_{1} \cdot \vec{d}_{2}\), (b) \(\vec{d}_{1} \times \vec{d}_{2}\), and \((\mathrm{c})\) the angle between \(\vec{d}_{1}\) and \(\vec{d}_{2} ?\)

Two vectors, \(\vec{r}\) and \(\vec{s}\), lie in the \(x y\) plane. Their magnitudes are \(4.50\) and \(7.30\) units, respectively, and their directions are \(320^{\circ}\) and \(85.0^{\circ}\), respectively, as measured counterclockwise from the positive \(x\) axis. What are the values of \((\) a \() \vec{r} \cdot \vec{s}\) and \((b) \vec{r} \times \vec{s} ?\)

What is the sum of the following four vectors in (a) unit-vector notation, and as (b) a magnitude and (c) an angle? $$ \begin{array}{ll} \vec{A}=(2.00 \mathrm{~m}) \hat{\mathrm{i}}+(3.00 \mathrm{~m}) \hat{\mathrm{j}} & \vec{B}: 4.00 \mathrm{~m}, \text { at }+65.0^{\circ} \\ \vec{C}=(-4.00 \mathrm{~m}) \hat{\mathrm{i}}+(-6.00 \mathrm{~m}) \hat{\mathrm{j}} & \vec{D}: 5.00 \mathrm{~m}, \text { at }-235^{\circ} \end{array} $$

A ship sets out to sail to a point \(120 \mathrm{~km}\) due north. An unexpected storm blows the ship to a point \(100 \mathrm{~km}\) due east of its starting point. (a) How far and (b) in what direction must it now sail to reach its original destination?

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