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