同济大学：《大学物理》课程教学资源（电子教案，英文版）第三章 牛顿定律

Newton's Laws

Newton’s Laws

Agenda today 1.Newton's Laws 2.Force on a body 3.Centripetal force 4.Non-inertial reference system

Agenda today 1. Newton’s Laws 2. Force on a body 3. Centripetal force 4. Non-inertial reference system

Newton's First Law of motion: Any object will keep its state of movement when it is left along. V =const (F=0)》 Inertia(惯性)：the property to keep one's state of movement Mass(质量)：the measure of the inertia of a body

Newton’s First Law of motion: Any object will keep its state of movement when it is left along. v  const （F  0）   Inertia(惯性） ：the property to keep one’s state of movement Mass（质量）: the measure of the inertia of a body

GOODYEAR

Newton's second Law of Motion The acceleration of an object is directly proportional to the net force and is inversely proportional to its mass,its direction is the direction of the net force. ma 或 F=m d布 dt Linear momentum(动量)：the product of object's mass and velocity Force(力)：The first derivative of linear momentum

Newton’s second Law of Motion The acceleration of an object is directly proportional to the net force and is inversely proportional to its mass,its direction is the direction of the net force. F ma    或 dt dv F m    Force（力）: The first derivative of linear momentum Linear momentum（动量）: the product of object’s mass and velocity

Newton's third law of motion Whenever one object exert a force on another one ,the another exert a force on the one same in magnitude and opposite in direction. F=- These forces(action and reaction)appears in pairs. This law implies the conservation law of momentum. the action force and reaction force are in the same nature

Newton’s third law of motion Whenever one object exert a force on another one ,the another exert a force on the one same in magnitude and opposite in direction. F  F   These forces( action and reaction) appears in pairs. This law implies the conservation law of momentum . the action force and reaction force are in the same nature

According to Newton's third law,the force I exert on the cart will cancel the force that the cart exert on me,so there is no need to pull the carriage a wise horse's reason

According to Newton’s third law, the force I exert on the cart will cancel the force that the cart exert on me,so there is no need to pull the carriage a wise horse’s reason

Forces in Nature Basic interactions The gravitation force(引力) The electromagnetic force(电磁力) The strong nuclear force(强相互作用力) The weak nuclear force(弱相互作用力)

Forces in Nature Basic interactions The gravitation force（引力） The electromagnetic force(电磁力） The strong nuclear force（强相互作用力） The weak nuclear force（弱相互作用力）