# G4 - What is Force • Accordig to Webster FORCE means many...

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Unformatted text preview: What is Force ? • Accordig to Webster, FORCE means many things: • strength or energy exerted or brought to bear • cause of motion or change • active power • capacity to persuade or convince • legal efficacy (. . . a law still in force. . . ) • military strength, etc., etc. • In Physics, FORCE is that agent which accelerates a mass and/or deforms an object (e.g., a spring) c circlecopyrt L.Frommhold . – p.24/24 What is Force ? • Pull hard enough: acceleration of mass (force of agent; tension of string) • Spring stretches (“deformation”) (convenient measurement of force !) c circlecopyrt L.Frommhold . – p.23/24 Examples of Force • Gravity (accelerates a falling object) • Impulse force (racket on tennis ball) • Friction (decelerates a moving mass) • Electric and magnetic forces, etc. • Note that force is a vector c circlecopyrt L.Frommhold . – p.22/24 Newton’s First Law Every object continues in a state of rest, or of uniform velocity in a straight line, as long as no net force acts on it. • Net force (definition): vector F net = vector F 1 + vector F 2 + · · · c circlecopyrt L.Frommhold . – p.21/24 About Newton’s First Law • A puck on (ideal) ice, once in motion, continues with constant speed forever. • A schoolbus comes to a sudden stop, and all the backpacks on the floor start to slide forward. Why? c circlecopyrt L.Frommhold . – p.20/24 Inertial Frames of Reference • Frames of reference may be attached to a moving vehicle and thus are moving relative to an observer...
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## This note was uploaded on 10/21/2009 for the course PHYSICS 30 taught by Professor Dr.lotharfrommhold during the Spring '09 term at University of Texas.

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G4 - What is Force • Accordig to Webster FORCE means many...

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