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Chapter 6 Force and Motion - II第 6 章 力與運動 ( 二 )
Chapter 6 Force and Motion - II
6-1 What is Physics?
6-2 Friction
6-3 Properties of Friction
6-4 The Drag Force and Terminal Speed
6-5 Uniform Circular Motion
6-1 What is Physics?
• frictional force 摩擦力• drag force 阻力• centripetal force 向心力
6-2 Friction
• static frictional force 靜摩擦力 fs• kinetic frictional force 動摩擦力 fk• cold-weld 冷熔接
The mechanism of sliding friction
6-3 Properties of Friction
,maxs s N
k k N
f F
f F
Sample Problem
Sample Problem
6-4 The Drag Force and Terminal Speed
• fluid 流體• drag force 阻力 D• drag coefficient 阻力係數 C• terminal speed 終端速率
21
2D C Av
• shot 鉛球• shot put 擲鉛球• sky diver 高空跳傘者• parachutist 跳傘者
6-5 Uniform Circular Motion
• A centripetal force accelerates a body by changing the direction of the body’s velocity without changing the body’s speed. 2
2
va
R
vF m
R
Sample Problem
Circular Motion
• loop-the-loop 騎單車翻圈子、倒飛觔斛• negative lift 負升力• Men in Black MIB 星際戰警• sedan 轎車• the verge of V-ing 瀕臨……• banked 傾斜 (tilted)
• bank 傾斜行駛
Sample problem
Sample Problem
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