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Newton’s Second Law/Force Body Diagrams. By:Brian Kidawa Chris Hayden Shoeb Siddiqui Mike Murphy. Terms. Force-Agent that results in accelerating or deforming an object. Net Force-sum of all forces on an object gravity-Attraction between two masses according to their mass.(9.8 m/s)
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Newton’s Second Law/Force Body Diagrams By:Brian Kidawa Chris Hayden Shoeb Siddiqui Mike Murphy
Terms • Force-Agent that results in accelerating or deforming an object. • Net Force-sum of all forces on an object • gravity-Attraction between two masses according to their mass.(9.8 m/s) • Weight-Force of gravity on an object • Normal Force-Force perpendicular to surface. • Acceleration-Change of velocity due to a force over time. • Equilibrium-Net force on an object is zero.
Newton’s Second Law • Newton’s Second Law states: acceleration of a body is directly proportional to the net force on it and inversely proportional to its mass. • F=ma
Concepts • Says that an unbalanced force causes a change on motion. • Most familiar form of Newton’s Second Law is F=ma. • If forces are unbalanced, acceleration occurs. • An object has equilibrium when all forces cancel out.
Reality Check! • Weapons (guns) • Cars • Solar System • People on chairs • Sports
Sample Problems • If the mass of a crate is 100 kg and sliding friction is 250 N, what is the acceleration of the crate when the pulling force is 500 N? • m=100 kg a=? Pf=500 N Ff=250 N • Fnet=ma Fnet=500-250 250N • 250 N=100kg * a a=2.5N/Kg
Sample Problems continued.. • An object of mass 70kg is accelerated by a force of 20 N. What’s is its acceleration? • F=20 N m=70kg a=? • 20 N= 70kg*a • a=.29 N/Kg
Quiz • A 75 kg person traveling at a constant velocity on ice skates experiences a force of 40 N. What is the person’s acceleration? • answer:a=0 m/s/s • What is the mass of an object that is accelerated at 25 m/s/s that is pushed with a force of 500 N. • answer: m=20 kg
Quiz continued… • A constant force acts on a 5 kg object and reduces its velocity from 7 m/s to 3 m/s in a time of 3 seconds. Find the amount of force acting on it. • answer: F=6.65 N • A stock boy pushes a 20 kg box of SPAM with a force of 70 N and it accelerates at 0.4 m/s/s. Find the net force on the SPAM box. • answer: 8N • A 60m kg man rides up in an elevator that is accelerating at 0.8 m/s/s. What is the net force on the man? • answer: 48 N