CH5%20Laws%20of%20Motion-1

# CH5%20Laws%20of%20Motion-1 - CH5LawsofMotion.notebook...

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CH5 Laws of Motion.notebook PHYS 2325 1 Oct 12­9:10 AM Chapter 5 Chapter 5 : The Laws of Motion 5.1 The Concept of Force 5.2 Newtons First Law and Inertial Frames 5.3 Mass 5.4 Newtons Second Law 5.5 The Gravitational Force and Weight 5.6 Newtons Third Law 5.7 Some Applications of Newtons Laws 5.8 Forces of Friction Oct 12­9:10 AM The Laws of Motion The description of an object in motion included its position, velocity, and acceleration. There was no consideration of what might influence that motion. Two main factors need to be addressed to answer questions about why the motion of an object will change. Forces acting on the object The mass of the object Dynamics studies the causes of motion. Will start with three basic laws of motion Formulated by Sir Isaac Newton Oct 12­9:10 AM Sir Isaac Newton 1642 – 1727 Formulated basic laws of mechanics Discovered Law of Universal Gravitation Invented form of calculus Many observations dealing with light and optics Section 5.1 Oct 12­9:10 AM Force Forces in everyday experience Push on an object to move it Throw or kick a ball May push on an object and not be able to move it Forces are what cause any change in the velocity of an object. Newton’s definition A force is that which causes an acceleration Section 5.1 Oct 12­9:10 AM Classes of Forces Contact forces involve physical contact between two objects Examples a, b, c Field forces act through empty space No physical contact is required Examples d, e, f Section 5.1 Oct 12­9:10 AM Fundamental Forces Gravitational force Between objects Electromagnetic forces Between electric charges Nuclear force Between subatomic particles Weak forces Arise in certain radioactive decay processes Note: These are all field forces. Section 5.1

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CH5 Laws of Motion.notebook PHYS 2325 2 Oct 12­9:10 AM More About Forces A spring can be used to calibrate the magnitude of a force. Doubling the force causes double the reading on the spring. When both forces are applied, the reading is three times the initial reading. Section 5.1 Oct 12­9:10 AM Vector Nature of Forces The forces are applied perpendicularly to each other. The resultant (or net) force is the hypotenuse. Forces are vectors, so you must use the rules for vector addition to find the net force acting on an object. Section 5.1 Oct 12­9:10 AM Newton’s First Law If an object does not interact with other objects, it is possible to identify a reference frame in which the object has zero acceleration. This is also called the law of inertia. It defines a special set of reference frames called inertial frames. We call this an
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## This note was uploaded on 09/01/2011 for the course PHY 303 taught by Professor Erskine/tsoi during the Spring '08 term at University of Texas.

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CH5%20Laws%20of%20Motion-1 - CH5LawsofMotion.notebook...

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