Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Newton's theorem of revolving orbits wikipedia , lookup
Electromagnetism wikipedia , lookup
Mass versus weight wikipedia , lookup
Fictitious force wikipedia , lookup
Fundamental interaction wikipedia , lookup
Nuclear force wikipedia , lookup
Centrifugal force wikipedia , lookup
Classical central-force problem wikipedia , lookup
What is a force? Pick up 2 sheets in the back Watch the book What am I doing in all of these demonstrations? I am applying a force Definition Any of FORCE push or pull that causes an object to change its current state of motion or shape Can forces be seen? No– only the result of the application of the force can be seen. Watch You the ball: can’t see the force I apply to the ball. You can only see the result of the force the ball moves What is the unit of force? A Newton- named after Sir Isaac Newton Abbreviation – capital N What A does it mean? force of 1 N gives an acceleration of 1 m/s/s to a 1kg mass. Forces can be used to change the state of motion of an object or change the shape of the object. Forces can result in start objects moving ACCELERATIONS Can stop moving objects Can change the direction of an object’s motion Can change the shape of an object Can Crumpling a piece of paper Sometimes you can exert a force on an object and no change in motion or shape occurs. These types of forces are called. balanced Definition forces of balanced force: A force that produces no change. A force that has an equal and opposing force. Equal in size and opposite in direction Example: A person sitting in a chair. (Force arrow diagram) 100 N 100 N Arrows symbolize forces. These arrows have both size (scientists call it magnitude) and direction. Therefore, force is a vector quantity. The forces we spoke of earlier, the ones that changed the state of motion of an object or the shape of the object are called UNBALANCED FORCES. This is the type of force needed to produce motion. Example : A person who breaks a chair by sitting on it. Unbalanced forces produce a net force. A net force causes a change in the current state of motion of an object. It can also cause the shape of an object to change. Example: Tug of war (Force arrow diagram) Net force = 5 N to the left Before we go any further we need to talk about types of forces. There are many types of forces but we will only touch on seven in detail. There are two others I’d like to mention: Nuclear force: The strong nuclear force is the force that holds the protons and neutrons together in the nucleus of atoms. Molecular force: The attraction of molecules for each other results in two kinds of forces. Cohesion-force of attraction between like molecules (ever do a belly flop?) Adhesion-force of attraction between unlike molecules (tape, glue-adhesives) Applied Force Gravity Force “weight” Normal Force Balanced forcesno change in current state of motion Frictional Force •Friction opposes motion •Must be contact between two surfaces Air Resistance •Unbalanced forces •object accelerates Air Resistance #2 •Piece of paper falling to the ground •Balanced forces •Object falls at a constant speed Tensional Force Teachers Win! Spring Force •Mass hanging on spring •Stretched spring •Spring wants to return to rest position Spring Force #2 •Compressed Spring •Spring wants to return to rest position Free Body Diagrams Divide the front side into 6 equal boxes Divide the back into 4 boxes Create the 10 diagrams for homework. Follow the directions Read the descriptions carefully.