Who Needs It ENERGY POTENTIAL Potential energy Stored

Who Needs It? ?

ENERGY: POTENTIAL & • Potential energy – Stored up energy or energy held in readiness KINETIC • Kinetic energy – Energy of motion

ENERGY: The ability to do work & cause change • POTENTIAL ENERGY – Stored-up energy, or energy held in readiness – EXAMPLES: • Elastic Potential Energy – Like slingshot or bungee cord • Gravitational Potential Energy – Like diver on diving board or light bulb in off position • KINETIC ENERGY – Energy of motion – EXAMPLES • moving bicycle • moving auto • high jumper jumping • runner

POTENTIAL ENERGY Energy stored or held in readiness Most potential

THE TRADE OFF Between Potential & Kinetic Energy

KINETIC ENERGY Energy of motion

TYPES OF ENERGY • MECHANICAL – Car, plane, wagon • THERMAL – Heat from moving molecules – Inside all matter; furnace • ELECTROMAGNETIC – Visible light, microwaves, radio waves • CHEMICAL – Batteries, matches, body cells • ELECTRICAL – Lightning, power lines • NUCLEAR – Nuclear power plants, atomic bomb, sun & stars

FORCES & MOTION • FORCE – A Push or a Pull • MOTION – A Change of Position or Location

FRICTION AS A FORCE • Strength of friction depends on: – Types of surfaces involved – How hard surfaces push together

TYPES OF FRICTION • SLIDING FRICTION – 2 solid surfaces – Strength depends on roughness of surfaces • ROLLING FRICTION – One solid rolls over the other – Much easier to move object • FLUID FRICTION – Solid moving through a liquid or gas – Less than sliding friction

GRAVITY AS A FORCE • FREE FALL – Object accelerates as it falls due to gravity – Object accelerates at rate of 9. 8 m/s 2 • Every second velocity increases by 9. 8 meters per second • @ 2 seconds velocity is 9. 8 m/s + 9. 8 m/s = 19. 6 m/s • @ 3 seconds velocity is 9. 8 m/s + 9. 8 m/s = 29. 4 m/s

GRAVITY AS A FORCE • AIR RESISTANCE – Type of fluid friction that opposes motion • WEIGHT – Measures force of gravity on object – Weight = Mass X Acceleration due to Gravity

WHAT MAKES OBJECTS START MOVING. . . STOP MOVING. . . SLOW DOWN. . . SPEED UP. . . or CHANGE DIRECTION?

NEWTON’S FIRST LAW • An object at rest remains at rest and an object in motion remains in motion unless acted upon by an outside force.

NEWTON’S SECOND LAW • THE FORCE EXERTED BY AN OBJECT IS RELATED TO ITS MASS & ITS ACCELERATION • AN OBJECTS ACCELERATION IS RELATED TO ITS MASS & THE FORCE REQUIRED TO MOVE IT • FORCE = MASS X ACCELERATION

WHAT AFFECTS WHAT? FORCE = MASS X ACCELERATION FORCE ACCELERATION MASS FORCE ACCELERATION

NEWTON’S THIRD LAW • For every action, there is an equal & opposite reaction

THE END