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2103-212 Dynamics, NAV, 2012 1 Chapter 6 Plane Kinetics of Rigid Bodies

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2103-212 Dynamics, NAV, 2012 1

Chapter 6

Plane Kinetics of

Rigid Bodies

2103-212 Dynamics, NAV, 2012 2

Introduction

6.1 Force, Mass, and Acceleration

(Newton’s laws of motion)

6.2 Work and Energy

6.3 Impulse and Momentum

6. Plane Kinetics

2103-212 Dynamics, NAV, 2012 3

Introduction

Relations between forces and motion of rigid body will be

studied.

For rigid bodies, translational and rotational motions must

be considered (for particles, only translational motion is).

We will consider only plane motion (2-D motion)

Translation

Rectilinear

Curvilinear

Fixed Axis Rotation

General Plane Motion

6. Plane Kinetics

2103-212 Dynamics, NAV, 2012 4

6-1 Force, Mass,

and Acceleration

2103-212 Dynamics, NAV, 2012 5

6-1 Force, Mass, and Acceleration 1. Introduction

2. Force Equation

3. Moment Equation (about G)

4. Kinetic Diagram

5. Moment Equation about Other Point

6. Translation

Rectilinear

Curvilinear

7. Fixed Axis Rotation

8. General Plane Motion

2103-212 Dynamics, NAV, 2012 6

A free body diagram is required.

Three Newton’s laws of Motion are used.

The second law has two equations,

force equation

moment equation

both applies simultaneously.

Proofs are in Chapter 4: Systems of Particles.

1. Introduction

6-1 Force, Mass, and Acceleration

2103-212 Dynamics, NAV, 2012 7

2. Force Equation 6-1 Force, Mass, and Acceleration

2103-212 Dynamics, NAV, 2012 8

3. Moment Equation (about G) 6-1 Force, Mass, and Acceleration

2103-212 Dynamics, NAV, 2012 9

4. Kinetic Diagram

6-1 Force, Mass, and Acceleration

2103-212 Dynamics, NAV, 2012 10

5. Moment Equation about Other Point 6-1 Force, Mass, and Acceleration

2103-212 Dynamics, NAV, 2012 11

6.1 Rectilinear Translation 6-1 Force, Mass, and Acceleration

2103-212 Dynamics, NAV, 2012 12

6.2 Curvilinear Translation 6-1 Force, Mass, and Acceleration

2103-212 Dynamics, NAV, 2012 13

7. Fixed Axis Rotation 6-1 Force, Mass, and Acceleration

2103-212 Dynamics, NAV, 2012 14

7. Fixed Axis Rotation

and

6-1 Force, Mass, and Acceleration

2103-212 Dynamics, NAV, 2012 15

7. Fixed Axis Rotation

Proof:

Parallel Axis Theorem

6-1 Force, Mass, and Acceleration

2103-212 Dynamics, NAV, 2012 16

7. Fixed Axis Rotation Radius of Gyration

6-1 Force, Mass, and Acceleration

2103-212 Dynamics, NAV, 2012 17

8. General Plane Motion

Same as before

6-1 Force, Mass, and Acceleration

2103-212 Dynamics, NAV, 2012 18

Example 1: A Moving Car

6-1 Force, Mass, and Acceleration

2103-212 Dynamics, NAV, 2012 19

Example 2: Swinging Pendulum

6-1 Force, Mass, and Acceleration

2103-212 Dynamics, NAV, 2012 20

Example 3: Concept Test 6-1 Force, Mass, and Acceleration

2103-212 Dynamics, NAV, 2012 21

Example 4: Car’s Door

6-1 Force, Mass, and Acceleration

2103-212 Dynamics, NAV, 2012 22

Example 5: Rolling Loop

6-1 Force, Mass, and Acceleration

2103-212 Dynamics, NAV, 2012 23

Example 6: A Translating Bar

6-1 Force, Mass, and Acceleration

2103-212 Dynamics, NAV, 2012 24

Example 7: Which one is the fastest?

6-1 Force, Mass, and Acceleration