Newton's Laws of Motion and Forces, Study notes of Physics

Download Newton's Laws of Motion and Forces and more Study notes Physics in PDF only on Docsity! 9/20/2008 1 More on forces and motion http://cartoonstock.com/directory/N/Newton.asp In the previous lecture • More than one force can be exerted on an object---the concept of total external force • Mechanical equilibrium: • When objects accelerate, their motion changes. .0F i   ,0F i   Graphs of accelerating objects Equations for accelerating objects • For a dropped ball (in vacuum), its acceleration is constant )vv( 2 1 v fiav  tvy av  tav  Hang time If the world record vertical standing jump is 1.25 m, how long is the person in the air? Use . 2 yi )g( 2 1 tvy t Lab this week , t x v ,      avx , t v x avx,      a Average velocity: Average acceleration: Motion in two dimensions! Stomp rockets! t y v ,      avy t v y avy,      a 9/20/2008 2 Newton: Who was he? He was a scientist, mathematician and theologian As Newton sat under the apple tree Newton’s First Law • Also called the law of inertia • Every object continues in a state of rest or of uniform speed in a straight line unless acted on a nonzero total force. • Everyday examples of Newton’s First Law Newton’s Second Law • The acceleration produced by the total force on an object is directly proportional to the total force, is in the same direction as the net force, and is inversely proportional to the mass of the object. • More concisely, . m F a tot    Newton’s Second Law Newton’s Second Law A skydiver jumps from a high-flying helicopter. She falls faster and faster through the air, does her acceleration increase, decrease, or stay the same?