Forces Types of Forces Effects of Forces Gravity, Mass and Weight Newton’s Laws Freefall

What is force? Common symbol: F Unit: Newton, N Equivalent base units: kg-m-s -2

Types of Forces Contact Force Contact Force  Push  Pull  Friction  Tension  Normal Force  Upthrust Bouyancy Bouyancy Lift Lift  Drag Resistance Resistance  Thrust Engine Engine Non-contact Force Non-contact Force  Gravitational Force Weight Weight  Electrical Force  Magnetic Force

Types of Forces: Contact Force pull Normal Force Friction Tension

Types of Forces: Contact Force UpthrustDrag

Replace it with your original text. Thrust Types of Forces: Contact Force Thrust

Replace it with your original text. Thrust Types of Forces: Contact Forces Lift

Replace it with your original text. Thrust Types of Forces: Non-Contact Forces Weight

Replace it with your original text. Types of Forces: Non-Contact Forces Magnetic Force Electrical Force

Mass versus Weight Mass Mass  Amount of matter in an object  unit: kilogram, kg  Does not change with location Weight Weight  Gravitational force on the object  Unit: Newton, N  Equal to Mass x acceleration due to gravity Mass x acceleration due to gravity m x g m x g Where g = 10 ms -2 Where g = 10 ms -2  Changes with location  On earth, always acting downward

Weight Normal force Weight Air resistance

Weight Normal Force Drag Friction Thrust

Weight Upthrust Drag Thrust

Effects of Forces Change shape Change shape  Rigid bodies Change the state of motion Change the state of motion  Move from rest  Speed up  Slow down  Stop  Change its direction Newton’s Laws Newton’s Laws

Change of Shape

extension

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

Newton’s First Law If no unbalanced force acts on a body then the body is in equilibrium. Law of Inertia

What is Inertia? The tendency of a body to resist changes in its state of motion. It is measured in terms of mass of a body.

When the forces are balanced The body does not move,or The body moves  At a constant speed  In 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 up  Or slows down  Or changes direction  Or 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

Freefall  Motion where only gravity is acting on the body  Air resistance is negligible  As the body falls, its Speed increases Acceleration is constant Acceleration = g

The Physics of Skydiving

The Physics of Falling with Air Resistance Air resistance increases with speed Terminal Velocity  The maximum speed of a falling object  When upward forces balance downward forces on the object

The End