Chapter_4 physics slides - Chapter 4 Units of Chapter 4 Force Newtons First Law of Motion Mass Newtons Second Law of Motion Newtons Third Law of Motion

Chapter_4 physics slides - Chapter 4 Units of Chapter 4...

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Chapter 4 Dynamics: Newton’s Laws of Motion 1 Units of Chapter 4 9 Force 9 Newton’s First Law of Motion 9 Mass 9 Newton’s Second Law of Motion 9 Newton’s Third Law of Motion 9 Weight—the Force of Gravity 9 Free-Body Diagrams 9 Problem Solving—A General Approach 2 4-1 Force A force is a push or pull . An object at rest needs a force to get it moving ; a moving object needs a force to change its velocity . 3 4-1 Force Force is a vector , having both magnitude and direction . The magnitude of a force can be measured using a spring scale. 4
4-1 Force Identifying forces… (a) Non-contact forces … arise between two objects even though they do not touch each other. Gravity . Weight Electromagnetic forces. Nuclear interaction forces. (b) Contact forces … arise when two objects touch each other. Push or pull . Tension act along the length of a rope. Normal forces … are perpendicular to a surface. Frictional forces … are parallel to a surface. 5 6 Isaac Newton ( 1642 – 1727) 7 4-2 Newton’s First Law of Motion This is Newton’s first law , which is often called the law of inertia : Every object continues in its state of rest, or of uniform velocity in a straight line, as long as no net force acts on it. F represents the force applied by the person and F fr represents the force of friction. 8