Forces

Push or pull between TWO masses

Forces Push or pull between TWO masses Measured in Newtons (N) –What is a Newton?

Forces Push or pull between TWO masses Measured in Newtons (N) –What is a Newton? Is force a vector?

Forces Push or pull between TWO masses Measured in Newtons (N) –What is a Newton? Is force a vector? (direction)

Forces Push or pull between TWO masses Measured in Newtons (N) –What is a Newton? Is force a vector? (direction) Force is a vector (magnitude and direction)

Forces Push or pull between TWO masses Measured in Newtons (N) –What is a Newton? Is force a vector? (direction) Force is a vector (magnitude and direction) –Typically shown with an arrow F

Long Range (Universal) Forces Forces that act at a distance – contact not necessary

Long Range (Universal) Forces Forces that act at a distance – contact not necessary Gravitational (F g ) – between two masses

Long Range (Universal) Forces Forces that act at a distance – contact not necessary Gravitational (F g ) – between two masses –Attraction (pull) only –Weakest of the four

Long Range (Universal) Forces Forces that act at a distance – contact not necessary Gravitational (F g ) – between two masses –Attraction (pull) only –Weakest of the four Electromagnetic (F E ) – between two charges

Long Range (Universal) Forces Forces that act at a distance – contact not necessary Gravitational (F g ) – between two masses –Attraction (pull) only –Weakest of the four Electromagnetic (F E ) – between two charges –Attraction or repulsion

Long Range (Universal) Forces Forces that act at a distance – contact not necessary Gravitational (F g ) – between two masses –Attraction (pull) only –Weakest of the four Electromagnetic (F E ) – between two charges –Attraction or repulsion Strong Nuclear – between subatomic particles (protons and neutrons) –Attraction

Long Range (Universal) Forces Forces that act at a distance – contact not necessary Gravitational (F g ) – between two masses –Attraction (pull) only –Weakest of the four Electromagnetic (F E ) – between two charges –Attraction or repulsion Strong Nuclear – between subatomic particles (protons and neutrons) –Attraction Weak Nuclear – subatomic stability

Short Range Forces Apparent contact necessary

Short Range Forces Apparent contact necessary Applied (F A )– basic push or pull

Short Range Forces Apparent contact necessary Applied (F A )– basic push or pull Tension (F T ) – along a rope, string, cable, chain Pulls only

Short Range Forces Apparent contact necessary Applied (F A )– basic push or pull Tension (F T ) – along a rope, string, cable, chain Pulls only Friction (F f ) – opposes motion between surfaces

Short Range Forces Apparent contact necessary Applied (F A )– basic push or pull Tension (F T ) – along a rope, string, cable, chain Pulls only Friction (F f ) – opposes motion between surfaces –Directed parallel to (along) surface

Short Range Forces Apparent contact necessary Applied (F A )– basic push or pull Tension (F T ) – along a rope, string, cable, chain Pulls only Friction (F f ) – opposes motion between surfaces –Directed parallel to (along) surface Normal (F N ) – supportive force out of a surface

Short Range Forces Apparent contact necessary Applied (F A )– basic push or pull Tension (F T ) – along a rope, string, cable, chain Pulls only Friction (F f ) – opposes motion between surfaces –Directed parallel to (along) surface Normal (F N ) – supportive force out of a surface –Directed perpendicular (normal) to surface –Not always “up”

Free-Body Diagrams (FBD) (Force Diagrams) Draw the object

Free-Body Diagrams (FBD) (Force Diagrams) Draw the object Define the system (objects involved)

Free-Body Diagrams (FBD) (Force Diagrams) Draw the object Define the system (objects involved) Draw forces as vector arrows –Show all forces as pulls

Free-Body Diagrams (FBD) (Force Diagrams) Draw the object Define the system (objects involved) Draw forces as vector arrows –Show all forces as pulls Draw FBD of book

Mass – amount of matter in an object unit: kilograms (kg) Weight – amount of gravitational force (F g ) pulling on a mass unit: Newtons (N) Lab – Determine how weight depends on the mass of an object.

Gravitational Force vs. Mass Lab Spring scale use F g ?? Accurate values Varied scales and mass amounts Mass in kilograms “Slope meaning” – use number and unit