Chapter 10: Problem 44
\(41-46\) . Find the horizontal and vertical components of the vector with given length and direction, and write the vector in terms of the vectors \(\mathbf{i}\) and \(\mathbf{j}\) . $$ |\mathbf{v}|=800, \quad \theta=125^{\circ} $$
Short Answer
Expert verified
The vector is \( \mathbf{v} = -458.88 \mathbf{i} + 655.36 \mathbf{j} \).
Step by step solution
01
Identify Vector Components
The problem provides the length (magnitude) of the vector and its direction. The horizontal component can be found using \[ v_x = |\mathbf{v}| \cos(\theta) \]and the vertical component using \[ v_y = |\mathbf{v}| \sin(\theta) \]where \(|\mathbf{v}|\) is the magnitude and \(\theta\) is the angle from the positive x-axis.
02
Calculate Horizontal Component
Use the formula for the horizontal component:\[ v_x = 800 \cos(125^{\circ}) \]Calculate \(\cos(125^{\circ})\) which is approximately \(-0.5736\). Then:\[ v_x = 800 \times (-0.5736) = -458.88 \]
03
Calculate Vertical Component
Use the formula for the vertical component:\[ v_y = 800 \sin(125^{\circ}) \]Calculate \(\sin(125^{\circ})\) which is approximately \(0.8192\). Then:\[ v_y = 800 \times 0.8192 = 655.36 \]
04
Write Vector in Terms of \(\mathbf{i}\) and \(\mathbf{j}\)
Combine the horizontal and vertical components to express the vector in terms of the unit vectors \(\mathbf{i}\) and \(\mathbf{j}\):\[ \mathbf{v} = -458.88 \mathbf{i} + 655.36 \mathbf{j} \].
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Horizontal Component
When we talk about the horizontal component of a vector, we're identifying the part of the vector that stretches along the horizontal axis, typically the x-axis. This component tells us how much of the vector runs left or right.
To find the horizontal component, use the formula:
In the example given with a magnitude of 800 and an angle of 125°, the calculation becomes:
To find the horizontal component, use the formula:
- \( v_x = ||\mathbf{v}| \cos(\theta) \)
In the example given with a magnitude of 800 and an angle of 125°, the calculation becomes:
- \( v_x = 800 \cos(125°) \)
- Using \(\cos(125°) \approx -0.5736\), the horizontal component \( v_x \) equates to approximately -458.88.
Vertical Component
The vertical component of a vector represents how much of the vector extends up or down along the vertical axis, usually the y-axis. It shows the vector's influence in the upward or downward direction.
To compute the vertical component, you can use the formula:
In the example provided, where \(|\mathbf{v}| = 800\) and \(\theta = 125°\), calculate:
To compute the vertical component, you can use the formula:
- \( v_y = |\mathbf{v}| \sin(\theta) \)
In the example provided, where \(|\mathbf{v}| = 800\) and \(\theta = 125°\), calculate:
- \( v_y = 800 \sin(125°) \)
- With \(\sin(125°) \approx 0.8192\), the vertical component \( v_y \) is about 655.36.
Unit Vectors
Unit vectors are fundamental in vector calculus and physics. They provide directions without scaling any length. A unit vector has a magnitude of exactly 1, and they are immensely useful for expressing vectors in a standardized way.
The most common unit vectors are:
The most common unit vectors are:
- \(\mathbf{i}\) - Represents the unit vector in the horizontal direction.
- \(\mathbf{j}\) - Represents the unit vector in the vertical direction.
- \(\mathbf{v} = -458.88 \mathbf{i} + 655.36 \mathbf{j}\)
Magnitude of a Vector
The magnitude of a vector is a measure of its length or size. Think of it as the distance from the origin of the vector to its endpoint in a standard coordinate system. It provides no direction, only size.
In our example, the magnitude was given as:\[ |\mathbf{v}| = 800 \].
Magnitude is calculated by combining both the horizontal and vertical components using the Pythagorean theorem:
In our example, the magnitude was given as:\[ |\mathbf{v}| = 800 \].
Magnitude is calculated by combining both the horizontal and vertical components using the Pythagorean theorem:
- \(|\mathbf{v}| = \sqrt{v_x^2 + v_y^2}\)