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Chapter 4 Forces and Newton’s Laws of Motion. Motion and Newton’s first law What is a force? Identifying forces Newton’s second law Free-body diagrams Newton’s third law. Topics:. Sample question:.
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Chapter 4 Forces and Newton’s Laws of Motion • Motion and Newton’s first law • What is a force? • Identifying forces • Newton’s second law • Free-body diagrams • Newton’s third law Topics: Sample question: These ice boats sail across the ice at great speeds. What gets the boats moving in the first place? What keeps them from going even faster? Slide 4-1
Reading Quiz 4. An action/reaction pair of forces A. point in the same direction. B. act on the same object. C. are always long-range forces. D. act on two different objects. Slide 4-6
Answer 4. An action/reaction pair of forces D. act on two different objects. Slide 4-7
... is a push or pull. ... acts on an object. ... requires an agent. ... is a contact force or a long-range force. ... is a vector. What Is a Force? A force... Slide 4-10
Galileo (1564-1642) Developed the idea of experimental science Re-examined natural motion of objects and how objects move Made astronomical observations that challenged Earth-centered solar system model.
Newton (1642-1727) Newton's work based on experiments of how objects interact. His laws of motion and law of gravity described how all objects interact with eachother.
Newton’s Zeroeth Law of Motion Objects are dumb - They have no memory of the past and cannot predict the future. Objects only know what acts directly on them in a given moment. Slide 2-34
Newton's Zeroeth Law of Motion DEMO - Pushing the cart on track
Identifying Forces:Freebody (Force) Diagrams and System Schema Slide 2-34
Free-Body Diagrams Slide 4-24
System Schema • Draw a diagram where you write down the name of each object in the system and then draw a solid circle drawn around it. Draw two sided arrows like this between the object circles of objects that interact (This illustrates all interactions between the objects in this diagram). Draw an additional dotted line around the block to indicate it is the object of interest. This diagram is called a system schema. • A system schema illustrates all the relevant interactions between the objects in a given physical situation
Newton's First Law of Motion Every object continues in a state of rest or a state of motion with a constant speed in a straight line unless acted on by an unbalanced force.
Newton's First Law of Motion DEMO - Air Puck motion DEMO - Smash the HAND DEMO - Tablecloth
What Causes Motion? In the absence of any forces acting on it, an object will continue moving forever. Motion needs no “cause.” Slide 4-8
Newton’s Second Law Slide 4-22
Normal Force Slide 4-15