Chapter 7 Kinetic Energy and Work 7 Chapter

Chapter 7 Kinetic Energy and Work 第 7章 動能與功

Chapter 7 Kinetic Energy and Work 7 -1 What is Physics? 7 -2 What is Energy? 7 -3 Kinetic Energy 7 -4 Work 7 -5 Work and Kinetic Energy 7 -6 Work Done by the Gravitational Force 7 -7 Work Done by a Spring Force 7 -8 Work Done by a General Variable Force 7 -9 Power

7 -1 What is Physics? • Energy 能量、能

7 -2 What is Energy? • Principle of Energy Conservation • Kinetic Energy 動能 • Work 功

7 -3 Kinetic Energy • Kinetic energy K is energy associated with the state of motion of an object. • Joule (J) 焦耳 • locomotive 機車（火車頭） • throttle 節流閥、節氣閥、油門

7 -4 Work • Work W is said to be done on the object by the force. • Work W is energy transferred to or from an object by means of a force acting on the object. Energy transferred to the object is positive work, and energy transferred from the object is negative work.

7 -5 Work and Kinetic Energy • A force does positive work when it has a vector component in the same direction as the displacement, and it does negative work when it has a vector component in the opposite direction. It does zero work when it has no such vector component. • Work-Kinetic Energy Theorem 功能定理

Sample Problem

Sample Problem

7 -6 Work Done by the Gravitational Force

Sample Problem

7 -7 Work Done by a Spring Force • Hooke’s law 虎克定律 • spring constant 彈性常數 • spring force constant 彈力常數

Sample Problem

7 -8 Work Done by a General Variable Force

Sample Problem

7 -9 Power • power 功率 • watt (W) 瓦特

Sample Problem