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Ch 10: Dynamics of Rotational Motion
Young & Freedman Calc - University Physics 14th Edition
Young & Freedman Calc14th EditionUniversity PhysicsISBN: 9780321973610Non è quello che usi tu?Cambia libro di testo
Capitolo 10, Problema 6b

A metal bar is in the xyxy-plane with one end of the bar at the origin. A force F→=(7.00N)i+(−3.00N)j\(\overrightarrow{F}\)=\(\left\)(7.00N\(\right\))i+(-3.00N)j is applied to the bar at the point x=3.00 mx=3.00\(\text{ m}\), y=4.00 my=4.00\(\text{ m}\). What are the magnitude and direction of the torque with respect to the origin produced by F→\(\overrightarrow{F}\)?

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First, understand that torque (τ) is a measure of the rotational force applied to an object. It is calculated using the cross product of the position vector (r) and the force vector (F). The formula for torque is τ = r × F.
Identify the position vector r from the origin to the point where the force is applied. In this case, r = (3.00 m)i + (4.00 m)j.
Write the force vector F, which is given as F = (7.00 N)i + (-3.00 N)j.
Calculate the cross product r × F. The cross product in two dimensions can be simplified using the determinant of a matrix: |i j k| |3.00 4.00 0| |7.00 -3.00 0|. Since the vectors are in the xy-plane, the k-component will give the magnitude of the torque.
Determine the magnitude of the torque, which is the absolute value of the k-component from the cross product. The direction of the torque is given by the right-hand rule, which indicates whether the rotation is clockwise or counterclockwise.

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Concetti chiave

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Torque

Torque is a measure of the rotational force applied to an object, calculated as the cross product of the position vector and the force vector. It determines how effectively a force can cause an object to rotate around a pivot point. The magnitude of torque is given by τ = rFsinθ, where r is the distance from the pivot, F is the force, and θ is the angle between r and F.
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Percorso guidato
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Net Torque & Sign of Torque

Cross Product

The cross product is a mathematical operation used to find a vector perpendicular to two given vectors in three-dimensional space. For vectors A and B, the cross product A × B results in a vector whose magnitude is |A||B|sinθ, where θ is the angle between A and B. In the context of torque, it helps determine the direction and magnitude of rotational force.
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Percorso guidato
10:30
Vector (Cross) Product and the Right-Hand-Rule

Vector Components

Vector components are the projections of a vector along the axes of a coordinate system, typically expressed in terms of i, j, and k unit vectors. Understanding vector components is crucial for calculating torque, as it involves breaking down the force vector into its x and y components to apply the cross product with the position vector, which also has x and y components.
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Vector Addition By Components
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