Book cover for College Physics: A Strategic Approach Volume 1

College Physics: A Strategic Approach Volume 1

Randall D. Knight, Brian Jones, Stuart Field

ISBN #9780321595492

2nd Edition

1,173 Questions

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23,429 Students Helped

Homework Questions

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Summary

Learning Objectives

Key Concepts

Example Problems

Explanations

Common Mistakes

Summary

This section emphasizes the fundamental concepts of rotational motion and dynamics. Key points include the use of the rigid-body model, the calculation and interpretation of angular velocity, angular acceleration, torque, and moment of inertia, and the parallels with linear motion. Problems involving rotational kinematics, gravitational torque, and rolling without slipping illustrate how these concepts are applied to real-world scenarios such as spinning disks, opening doors, and designing mechanical systems.

Learning Objectives

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Key Concepts

CONCEPT

DEFINITION

Definition: The practical application of Newton’s three laws to analyze and solve problems involving static equilibrium and dynamic motion.

The practical application of Newton’s three laws to analyze and solve problems involving static equilibrium and dynamic motion. •

Example Problems

Example 1

To throw a discus, the thrower holds it with a fully outstretched arm. Starting from rest, he begins to turn with a constant angular acceleration, releasing the discus after making one complete revolution. The diameter of the circle in which the discus moves is about $1.8 \mathrm{~m}$. If the thrower takes $1.0 \mathrm{~s}$ to complete one revolution, starting from rest, what will be the speed of the discus at release?

Example 2

A computer hard disk starts from rest, then speeds up with an angular acceleration of $190 \mathrm{rad} / \mathrm{s}^{2}$ until it reaches its final angular speed of 7200 rpm. How many revolutions has the disk made $10.0 \mathrm{~s}$ after it starts up?

Example 3

The crankshaft in a race car goes from rest to 3000 rpm in 2.0 s. a. What is the crankshaft's angular acceleration? b. How many revolutions does it make while reaching $3000 \mathrm{rpm} ?$

Example 4

Reconsider the situation in Example $7.5 .$ If Luis pulls straight down on the end of a wrench that is in the same orientation but is $35 \mathrm{~cm}$ long, rather than $20 \mathrm{~cm},$ what force must he apply to exert the same torque?

Example 5

Balls are attached to light rods and can move in horizontal circles as shown in Figure P7.5. Rank in order, from smallest to largest, the torques $\tau_{1}$ to $\tau_{4}$ about the centers of the circles. Explain.

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Step-by-Step Explanations

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Common Mistakes

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