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1、 Copyright 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley.Chapter 12. Rotation of a Rigid Body Not all motion can be described as that of a particle. Rotation requiresthe idea of an extended object. This diver is moving toward the water along a parabolic trajectory, and shes rota
2、ting rapidly around her center of mass.Chapter Goal: To understand the physics of rotating objects. Copyright 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley.Topics: Rotational Motion Rotation About the Center of Mass Rotational Energy Calculating Moment of Inertia Torque Rotation
3、al Dynamics Rotation About a Fixed Axis Static Equilibrium Rolling Motion The Vector Description of Rotational Motion Angular Momentum of a Rigid Body Chapter 12. Rotation of a Rigid Body Copyright 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley.Chapter 12. Reading Quizzes Copyrig
4、ht 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley.A new way of multiplying two vectors is introduced in this chapter. What is it called?A. Dot ProductB. Scalar ProductC. Tensor ProductD. Cross ProductE. Angular Product Copyright 2008 Pearson Education, Inc., publishing as Pearson
5、 Addison-Wesley.A new way of multiplying two vectors is introduced in this chapter. What is it called?A. Dot ProductB. Scalar ProductC. Tensor ProductD. Cross ProductE. Angular Product Copyright 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley.Moment of inertia is A. the rotational
6、 equivalent of mass.B. the point at which all forces appear to act.C. the time at which inertia occurs.D. an alternative term for moment arm. Copyright 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley.Moment of inertia is A. the rotational equivalent of mass.B. the point at which a
7、ll forces appear to act.C. the time at which inertia occurs.D. an alternative term for moment arm. Copyright 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley.A rigid body is in equilibrium ifA.B.C. neither A nor B.D. either A or B.E. both A and B. Copyright 2008 Pearson Education,
8、Inc., publishing as Pearson Addison-Wesley.A rigid body is in equilibrium ifA.B.C. neither A nor B.D. either A or B.E. both A and B. Copyright 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley.Chapter 12. Basic Content and Examples Copyright 2008 Pearson Education, Inc., publishing
9、as Pearson Addison-Wesley.Rotational Motion The figure shows a wheel rotating on an axle. Its angular velocity isThe units of are rad/s. If the wheel is speeding up or slowing down, its angular acceleration isThe units of are rad/s2. Copyright 2008 Pearson Education, Inc., publishing as Pearson Addi
10、son-Wesley.Rotational Motion Copyright 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley.EXAMPLE 12.1 A rotating crankshaftQUESTION: Copyright 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley.EXAMPLE 12.1 A rotating crankshaft Copyright 2008 Pearson Education, Inc.
11、, publishing as Pearson Addison-Wesley.EXAMPLE 12.1 A rotating crankshaft Copyright 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley.EXAMPLE 12.1 A rotating crankshaft Copyright 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley.EXAMPLE 12.1 A rotating crankshaft Co
12、pyright 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley.Rotation About the Center of MassAn unconstrained object (i.e., one not on an axle or a pivot) on which there is no net force rotates about a point called the center of mass. The center of mass remains motionless while every
13、other point in the object undergoes circular motion around it. Copyright 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley.Rotation About the Center of MassThe center of mass is the mass-weighted center of the object. Copyright 2008 Pearson Education, Inc., publishing as Pearson Add
14、ison-Wesley.Rotational EnergyA rotating rigid body has kinetic energy because all atoms in the object are in motion. The kinetic energy due to rotation is called rotational kinetic energy.Here the quantity I is called the objects moment of inertia.The units of moment of inertia are kg m2. An objects
15、 moment of inertia depends on the axis of rotation. Copyright 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley. Copyright 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley.EXAMPLE 12.5 The speed of a rotating rodQUESTION: Copyright 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley.EXAMPLE 12.5 The speed of a rotating rod Copyright 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley.EXAMPLE 12.5 The speed of a rotating rod Copyright 2008 Pearson Education, Inc., publishing a
