 # Forces in 1 Dimension Chapter 4. 4.1 Force and Motion Force is push or pull exerted on object Forces change motion –Makes it important to know the forces.

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Forces in 1 Dimension Chapter 4

4.1 Force and Motion Force is push or pull exerted on object Forces change motion –Makes it important to know the forces on an object Force diagrams (free body diagrams) show all forces acting on object –Both direction and magnitude – vector –Define system

Contact and Field Forces Contact – touching Field – non-contact (not touching) Every touch generates force Table 4-2, pg 94

Force and Acceleration Forces change motion Newton’s 2 nd Law –a = F net /m –Net forces and mass will affect the acceleration of an object Applying a force changes the object’s motion – generates an acceleration Changing mass, changes forces

Newton’s 1 st Law “An object that is at rest will remain at rest, and an object that is moving will continue to move in a straight line with constant speed, if and only if the net force acting on that object is zero” Inertia – tendency of an object to resist change –Not a force Equilibrium – net force on object is zero

4.2 Using Newton’s Laws Weight – gravitational force acting on object –Changes depending on where you are in Universe Scales – How it Works, pg 110 Apparent weight – weight changes with motion –Example: elevator –Weightlessness – apparent weight is zero No contact forces pushing up on object

Drag Force Particles of air exert forces on an object –Often is a huge force Drag force – force exerted by a fluid on an object moving through the fluid –Direct relationship – increase speed, increase drag force –Affected by size and shape of object, and temperature and viscosity of fluid

Terminal Velocity Constant velocity is reached when drag force equals gravitational force

4.3 Interaction Forces Interaction pairs Newton’s 3 rd Law states that all forces come in pairs –One doesn’t cause the other –Because there is one, there is the other –Equal in magnitude and opposite in direction –2 force diagrams – each one contains one of the forces in the interaction pair

The Normal Force Support force Perpendicular contact force exerted by a surface on another object

Lab Force table lab Newton’s second lab

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