forces types of forces effects of forces gravity, mass and weight newton’s laws freefall

ForcesForces

Types of ForcesTypes of Forces

Effects of ForcesEffects of Forces

Gravity, Mass and WeightGravity, Mass and Weight

Newton’s LawsNewton’s Laws

FreefallFreefall

What is force?What is force?

Common symbol: FCommon symbol: FUnit: Newton, NUnit: Newton, N

Equivalent base units: kg-m-sEquivalent base units: kg-m-s-2-2

Types of ForcesTypes of Forces

Contact ForceContact Force PushPush PullPull FrictionFriction TensionTension Normal ForceNormal Force Upthrust Upthrust

BouyancyBouyancyLiftLift

DragDragResistanceResistance

ThrustThrustEngineEngine

Non-contact ForceNon-contact Force Gravitational ForceGravitational Force

WeightWeight Electrical ForceElectrical Force Magnetic ForceMagnetic Force

Types of Forces: Contact ForceTypes of Forces: Contact Force

pullNormal Force

Friction

Tension

Types of Forces: Contact ForceTypes of Forces: Contact Force

Upthrust

Drag

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Thrust

Types of Forces: Contact Force

Thrust

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Thrust

Types of Forces: Contact Forces

Lift

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Thrust

Types of Forces: Non-Contact Forces

Weight

Weight

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Types of Forces: Non-Contact Forces

Magnetic ForceElectrical Force

Mass versus WeightMass versus Weight

MassMassAmount of matter in an Amount of matter in an

objectobjectunit: kilogram, kgunit: kilogram, kgDoes not change with Does not change with

locationlocation

WeightWeightGravitational force on Gravitational force on

the objectthe objectUnit: Newton, NUnit: Newton, NEqual toEqual to

Mass x acceleration Mass x acceleration due to gravitydue to gravity

m x gm x gWhere g = 10 msWhere g = 10 ms-2-2

Changes with locationChanges with locationOn earth, always acting On earth, always acting

downwarddownward

Weight

Normal force

Weight

Air resistance

Weight

Normal Force

Drag

Friction

Thrust

Weight

Upthrust

Drag Thrust

Effects of ForcesEffects of Forces

Change shapeChange shapeRigid bodiesRigid bodies

Change the state of motionChange the state of motionMove from restMove from restSpeed upSpeed upSlow down Slow down StopStopChange its directionChange its direction

Newton’s LawsNewton’s Laws

Change of Shape

extension

Who is Isaac Newton?Who is Isaac Newton?

“Nature and Nature's laws lay hid in night:God said, Let Newton be! and all was light.”

Newton’s Third Law

For every action there is an equal

and opposite reaction

Law of Action and Reaction

Action and Reaction Forces

Action and Reaction Forces

Newton’s First Law

If no unbalanced force acts on a body then the

body is in equilibrium.

Law of Inertia

What is What is InertiaInertia??

The tendency of a body to resist changes in The tendency of a body to resist changes in its state of motion.its state of motion.

It is measured in terms of mass of a body.It is measured in terms of mass of a body.

When the forces are balanced

The body does not move,orThe body moves

At a constant speedIn the same direction

Balanced forces

Balanced Forces

The book stays still!

Balanced Forces

The airplane moves forwards at constant speed!

Balanced Forces

The car moves at constant speed!

Drag

Friction

Thrust

Your Turn!

Question #1, page 104

Newton’s Second Law

An unbalanced force changes the motion of an object. It speeds upOr slows downOr changes directionOr changes speed and direction

Acceleration change in motion

Equation

a = force

mass

Unbalanced Forces

The car moves from rest.

The car speeds up.

Unbalanced Forces

The car slows down to stop.

The car slows down.

The Physics of Falling

The Physics of Falling

Freefall Motion where only gravity is acting on the bodyAir resistance is negligibleAs the body falls, its

Speed increasesAcceleration is constantAcceleration = g

The Physics of Skydiving

The Physics of Falling with Air Resistance

Air resistance increases with speedTerminal Velocity

The maximum speed of a falling objectWhen upward forces balance downward forces

on the object

The End