motion and newton’s first law what is a force? identifying forces newton’s second law
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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:. - PowerPoint PPT PresentationTRANSCRIPT
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
• Motion and Newton’s first law
• What is a force?
• Identifying forces
• Newton’s second law
• Free-body diagrams
• Newton’s third law
Chapter 4Forces and Newton’s Laws of Motion
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
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley.
Reading Quiz
4. An action/reaction pair of forcesA. 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
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4. An action/reaction pair of forces
D. act on two different objects.
Slide 4-7
Answer
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What Is a Force?
A force...
... is a push or pull. ... acts on an object.
... requires an agent.
... is a vector. ... is a contact force or a long-range force.
Slide 4-10
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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.
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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 each other.
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley. Slide 2-34
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.
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Newton's Zeroeth Law of Motion
DEMO - Pushing the cart on track
Copyright © 2007, Pearson Education, Inc., Publishing as Pearson Addison-Wesley. Slide 2-34
Identifying Forces:Freebody (Force) Diagrams and System Schema
Michael Laura
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Free-Body Diagrams
Slide 4-24
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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
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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.
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Newton's First Law of Motion
DEMO - Air Puck motion
DEMO - Smash the HAND
DEMO - Tablecloth
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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
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Newton’s Second Law
Slide 4-22
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Normal Force rn
Slide 4-15