* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Newton`s Laws Notes
Survey
Document related concepts
Coriolis force wikipedia , lookup
Jerk (physics) wikipedia , lookup
Hunting oscillation wikipedia , lookup
Modified Newtonian dynamics wikipedia , lookup
Mass versus weight wikipedia , lookup
Classical mechanics wikipedia , lookup
Fictitious force wikipedia , lookup
Equations of motion wikipedia , lookup
Newton's theorem of revolving orbits wikipedia , lookup
Rigid body dynamics wikipedia , lookup
Centrifugal force wikipedia , lookup
Centripetal force wikipedia , lookup
Transcript
Laws of Motion Mrs. Wolfe “If I have seen far, it is because I have stood on the shoulders of giants.” - Sir Isaac Newton (referring to Galileo) What is Force? • Force – a push or pull that one object exerts on another – What forces are being exerted on the football? Fkick Fgrav Draw a diagram showing the forces… • A girl is hanging from a bar held from the ceiling by two ropes. Draw a diagram of … • A flying squirrel is gliding from a tree to the ground. Try one more … • A piano is pushed to the right across the room. Balanced & Unbalanced forces • Which diagram(s) show BALANCED forces? Balanced Forces –Forces acting on an object that are opposite in direction and equal in size –Causes no change in velocity Time for a DEMO! • UNBALANCED forces cause a CHANGE IN VELOCITY (acceleration)! Which object(s) will ACCELERATE? Time for a WS! Unbalanced Forces & Motion WS The Big Misconception Read The Big Misconception Handout! Anna is right!! • These are BALANCED FORCES • No ACCELERATION • That means, NO CHANGE IN VELOCITY! • It could be moving, but it will keep moving at a constant speed in the same direction. • It could be at rest, but it will remain at rest. Forces DO NOT CAUSE MOTION! • FORCES CAUSE ACCELERATION! NET FORCE • Net Force = OVERALL FORCE • Force is measured in Newtons (N). • What is the NET FORCE on each object? 400 N 200 N 20 N Got it? Time for a WS! Force & Acceleration WS Newton’s First Law of Motion • An object at rest will remain at rest and an object in motion will continue moving at a constant velocity unless acted upon by an unbalanced force. • Things are LAZY…they keep doing what they’re already doing unless an UNBALANCED force causes a change! The Law of Inertia • Newton’s First Law of Motion –“Law of Inertia” • Inertia –Laziness –tendency of an object to resist any change in its motion –increases as mass increases In a nutshell… Demo: • Magic Golf Balls Demo: • Magic Coins More examples… How fast are you going when your face hits the pavement? Time for a Lab! • 1st Law of Motion Lab Demo: • Tossing a ball in a car (moving at a constant velocity). Where does it land? Time for a WS! • 1st Law of Motion WS Newton’s Second Law of Motion • Force = Mass x Acceleration F: (N) m: (kg) a: (m/s2) 1 N = 1 kg ·m/s2 F = ma F m a Time for a WS! • 2nd Law WS Demo: Time for a Lab! • 2nd Law Lab Demo: Back to the BIG MISCONCEPTION! • Why does it take an UNBALANCED force to cause an acceleration? Because F = m • a Fnet = 0 0=m•a A=0 It can’t accelerate! Demo: How does a CONSTANT VELOCITY affect FORCE? Newton’s Third Law of Motion • When one object exerts a force on a second object, the second object exerts an equal but opposite force back on the first. Demo: Problem: –How can a horse pull a cart if the cart is pulling back on the horse with an equal but opposite force? –Aren’t these “balanced forces” resulting in no acceleration? NO!!! Answer: –forces are equal and opposite but act on different objects –they are not “balanced forces” –Balanced forces act on the SAME OBJECT Demo: Problem: –A high-speed truck and a BUG have a head-on collision. The bug is crushed, while nothing happens to the truck. Do they hit each other with equal force? Answer: –Yes! Equal, but Opposite Forces! –The force acting on the bug is enough to crush the bug. The same force acting on the truck isn’t enough to hurt the truck. Time for a WS! • 3rd Law WS Identify the Action-Reaction Force Pairs Identify 2 Action-Reaction Force Pairs Identify 5 Action-Reaction Force Pairs Time for a Lab! • 3rd Law Lab Do you understand? Time for a Review WS! May the NET FORCE be with you!