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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: 9780137344796Not the one you use?Change textbook
Chapter 3, Problem 24b

Use geometry and trigonometry to determine the magnitude and direction of G = E+F.

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Step 1: Identify the components of the vectors E and F. From the diagram, vector E (green arrow) lies along the x-axis with a magnitude of 3 units, so its components are E_x = 3 and E_y = 0. Vector F (purple arrow) has a magnitude of 2 units and is at an angle θ above the positive x-axis. Its components can be expressed as F_x = 2 * cos(θ) and F_y = 2 * sin(θ).
Step 2: Add the components of the vectors E and F to find the components of vector G. The x-component of G is G_x = E_x + F_x, and the y-component of G is G_y = E_y + F_y. Substitute the values: G_x = 3 + 2 * cos(θ) and G_y = 0 + 2 * sin(θ).
Step 3: Calculate the magnitude of vector G using the Pythagorean theorem. The magnitude |G| is given by |G| = sqrt(G_x^2 + G_y^2). Substitute the expressions for G_x and G_y: |G| = sqrt((3 + 2 * cos(θ))^2 + (2 * sin(θ))^2).
Step 4: Determine the direction of vector G relative to the positive x-axis. The direction φ can be calculated using the formula φ = arctan(G_y / G_x). Substitute the expressions for G_x and G_y: φ = arctan((2 * sin(θ)) / (3 + 2 * cos(θ))).
Step 5: Interpret the results. The magnitude |G| represents the length of the resultant vector, and the angle φ gives its direction relative to the positive x-axis. Ensure that the angle is expressed in degrees or radians as required by the problem.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Vector Addition

Vector addition involves combining two or more vectors to determine a resultant vector. This is done by adding the corresponding components of the vectors. In a Cartesian coordinate system, the x and y components of each vector are summed separately to find the total vector's magnitude and direction.
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Trigonometry is essential for analyzing vectors, particularly when determining their components. The sine and cosine functions are used to resolve a vector into its x and y components based on the angle it makes with the axes. This allows for the calculation of the resultant vector's magnitude and direction using geometric relationships.
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