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Ch 03: Vectors and Coordinate Systems
Knight Calc - Physics for Scientists and Engineers 5th Edition
Knight Calc5th EditionPhysics for Scientists and EngineersISBN: 9780137344796Non è quello che usi tu?Cambia libro di testo
Capitolo 3, Problema 11d

Draw each of the following vectors, label an angle that specifies the vector's direction, then find its magnitude and direction.
a→=(20i+10j)m/s2\(\overrightarrow{\mathbf{a}\)}=(20\(\mathbf{i}\)+10\(\mathbf{j}\))\,\(\text{m/s}\)^2

Guida verificata passo dopo passo
1
Step 1: Understand the vector components. The vector \( \mathbf{a} \) is given as \( \mathbf{a} = 20\mathbf{i} + 10\mathbf{j} \), where \( \mathbf{i} \) represents the x-component and \( \mathbf{j} \) represents the y-component. This means the x-component of the vector is 20 m/s², and the y-component is 10 m/s².
Step 2: Draw the vector. On a Cartesian coordinate system, plot the x-component (20 m/s²) along the positive x-axis and the y-component (10 m/s²) along the positive y-axis. The vector \( \mathbf{a} \) is represented as the diagonal of the rectangle formed by these components, starting from the origin.
Step 3: Calculate the magnitude of the vector. Use the Pythagorean theorem: \( |\mathbf{a}| = \sqrt{(a_x)^2 + (a_y)^2} \), where \( a_x = 20 \) m/s² and \( a_y = 10 \) m/s². Substitute these values into the formula to find the magnitude.
Step 4: Determine the direction of the vector. The direction is given by the angle \( \theta \) that the vector makes with the positive x-axis. Use the formula \( \theta = \tan^{-1}\left(\frac{a_y}{a_x}\right) \), where \( a_x = 20 \) m/s² and \( a_y = 10 \) m/s². Substitute these values to find the angle.
Step 5: Label the vector. On your diagram, label the vector \( \mathbf{a} \) with its magnitude and the angle \( \theta \) you calculated. Ensure the angle is measured counterclockwise from the positive x-axis.

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Vector Representation

Vectors are quantities that have both magnitude and direction, represented in a coordinate system. In this case, the vector a = (20i + 10j) m/s² can be visualized in a two-dimensional plane, where 'i' represents the x-component and 'j' represents the y-component. Understanding how to graphically represent vectors is essential for visualizing their direction and magnitude.
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Magnitude of a Vector

The magnitude of a vector is a measure of its length, calculated using the Pythagorean theorem. For the vector a = (20i + 10j) m/s², the magnitude can be found using the formula |a| = √(x² + y²), where x and y are the components of the vector. This concept is crucial for determining how strong or large the vector is in physical terms.
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Direction of a Vector

The direction of a vector is specified by the angle it makes with a reference axis, typically the positive x-axis. This angle can be calculated using the tangent function, where θ = arctan(y/x). For the vector a = (20i + 10j) m/s², finding the angle helps in understanding how the vector is oriented in space, which is important for applications in physics.
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