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Unformatted text preview: 1 PHY 2053C College Physics A Spring 2004 Today: Dynamics: Newtons Laws of Motion Forces Friction, normal force, etc. Newton's laws (1, 2) Motion, Forces, Energy, Heat, Waves Dr. David M. Lind Dr. Kun Yang Dr. David Van Winkle L5Ch4 The net force acting on an object equals its mass times acceleration . Newton's Three Laws of Motion F m a Sir Issac Newton (1642-1727) All objects continue in their state of rest or of uniform speed in a straight line unless acted on by a net force Newtons Second Law: Newtons First Law: Newtons Third Law: Whenever an object exerts a force on a second object, the second object exerts an equal and opposite force on the first. We need to understand Forces! 2 Forces Most of you intuitively know the effect of forces : To set an object in motion , or change its state of motion To deform an object (See also Chapter 9) Unit of force : 1Newton = 1 N = 1kg . m/s 2 In Physics, forces are vectors , with both magnitude and direction. Forces add up as vectors, the sum of all forces acting on one object is called the net force . Forces Common Types of Forces include: Gravity F = mg Forces between collections of atoms or molecules: Friction opposes motion Normal Force opposes penetration Tension opposes separation or compression On (sub-)atomic level...
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