Chapter 11: Problem 40
In Exercises \(32-52,\) for the given vector \(\vec{v}\), find the magnitude \(\|\vec{v}\|\) and an angle \(\theta\) with \(0 \leq \theta<360^{\circ}\) so that \(\vec{v}=\|\vec{v}\|\langle\cos (\theta), \sin (\theta)\rangle\) (See Definition 11.8.) Round approximations to two decimal places. $$ \vec{v}=\langle 0, \sqrt{7}\rangle $$
Short Answer
Step by step solution
Understand the vector components
Calculate the magnitude of the vector
Find the angle \(\theta\)
Verification
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Vector Components
For a two-dimensional vector \( \vec{v} \) represented as \( \langle a, b \rangle\), \( a \) and \( b \) are its components along the x-axis and y-axis, respectively. These components can be thought of as coordinates in the vector space.
For instance, in the given vector \( \vec{v} = \langle 0, \sqrt{7} \rangle\), it shows:
- \(<0>\) along x-axis — indicating no movement in this direction.
- \(<\sqrt{7>}\) along y-axis — showing the vector's actual movement is upward in the y-direction.
Angle Between Vectors
In our exercise, the angle is defined with respect to the positive x-axis. The vector \( \vec{v} = \langle 0, \sqrt{7} \rangle \) is entirely along the positive y-axis. Thus, there is a right angle or \( 90^\circ \) gap from the positive x-axis.
This concept is crucial when:
- Mapping the direction of vectors.
- Determining fields such as mechanical physics where directionality is key.
Trigonometric Functions
For a vector \( \vec{v} = \|\vec{v}\|\langle \cos(\theta), \sin(\theta) \rangle \), the use of sine and cosine helps represent its direction in a coordinate system. In our example:
- \(\cos(90^\circ) = 0\)
- \(\sin(90^\circ) = 1\)
- Accurate conversion of angular data into linear components.
- Analysis of confined space problems in physics and engineering.
- Better grasp on vector manipulation for rotation and movement.
Calculation of Vector
\[ \|\vec{v}\| = \sqrt{a^2 + b^2} \]
For our vector \( \vec{v} = \langle 0, \sqrt{7} \rangle \), the calculation simplifies to \( \|\vec{v}\| = \sqrt{0^2 + (\sqrt{7})^2} = \sqrt{7} \).
This concise process involves:
- Identifying vector components \(a\) and \(b\).
- Applying the magnitude formula to compute the length.
- Force and motion description in physics.
- Spatial dynamics in engineering tasks.
- General problem-solving involving directions and rates of change.
Precalculus
Precalculus introduces vectors as arrows indicating direction and magnitude, essential for physics and engineering. Understanding involves:
- Breaking down a vector into components.
- Applying trigonometric principles to determine angles.
- Enabling learners to predict motions and forces analytically.
- Facilitating computation of vector-related problems.