Outline ·§2.1 Newton's Laws of Motion -Force Four fundamental forces Newton's law of universal gravitation Contact Noncontact forces ● The Principle of Force Superposition -Newton's Laws -Application of Newton's Laws 2.2 Galilean Principle of Relativity Noninertial Reference Frames 上海交大董占海 16
上海交大 董占海 16 Outline •§2.1 Newton’s Laws of Motion –Force • Four fundamental forces • Newton’s law of universal gravitation • Contact & Noncontact forces • The Principle of Force Superposition –Newton’s Laws –Application of Newton’s Laws •§ 2.2 Galilean Principle of Relativity & Noninertial Reference Frames
3.CONTACT NONCONTACT FORCES Four fundamental force:Noncontact Contact force: A PULL A PUSH 17 上海交大董占海
上海交大 董占海 17 3. CONTACT & NONCONTACT FORCES A PULL A PUSH Four fundamental force: Noncontact Contact force:
·Elastic force L Hook's law F=-kxi k:倔强系数xi:端点之位移 上海交大董占海 18
上海交大 董占海 18 • Elastic force ikxF r r −= k：倔强系数 ix : . 端点之位移 r x i r Hook’s law o
+Frictional force static friction f'sm LsN where u is the coefficient of static friction 19 上海交大董占海
上海交大 董占海 19 Nf = μ ssm •Frictional force where μs is the coefficient of static frictionT// static friction
kinetic friction f=uN where uk is the coefficient of the kinetic friction. Maximum value of fs fis approximately constant Breakaway 0 Time 20 上海交大董占海
上海交大 董占海 20 Nf = μ kk where μk is the coefficient of the kinetic friction. kinetic friction