WESBURY COLLEGE OF SCIENCE. 2013 GR 12 PHYSICAL SCIENCES INTERVENTION FOR SCIENCE LEARNERS SCIENCE DEPARTMENT PROJECT FOUNDATIONS OF LEARNING 2013-09-01. 1. KNOWLEDGE AREAS. MECHANICS CHEMICAL CHANGE WAVES, LIGHT, SOUND MATTER AND MATERIALS ELECTRICITY AND MAGNETISM
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WESBURY COLLEGE OF SCIENCE 2013 GR 12 PHYSICAL SCIENCES INTERVENTION FOR SCIENCE LEARNERS SCIENCE DEPARTMENT PROJECTFOUNDATIONS OF LEARNING 2013-09-01 1
KNOWLEDGE AREAS MECHANICS CHEMICAL CHANGE WAVES, LIGHT, SOUND MATTER AND MATERIALS ELECTRICITY AND MAGNETISM CHEMICAL SYSTEMS 2
KNOWLEDGE AREAMECHANICS THEMES • FORCE, MOMENTUM AND IMPULS (GR 11 MECHANICS) • MOMENTUM (GR 12 MECHANICS) • VERTICAL PROJECTILE MOTION (GR 12 MECHANICS) • FRAMES OF REFERENCE (GR 12 MECHANICS) • WORK, POWER AND ENERGY (GR 12 MECHANICS)
FORCE, MOMENTUM AND IMPULSE FORCE DIAGRAM • FREE BODY DIAGRAMS • OBJECT REPRESENT A DOT • FORCES ARE DRAWN AS ARROWS POINTING AWAY FROM THE • DOT • LENGTH OF ARROW REPRESENTS SIZE OF FORCE • POINT OF ARROW INDICATES THE DIRECTION OF THE FORCE FREE BODY DIAGRAM
FORCE, MOMENTUM AND IMPULSE NEWTONS THIRD LAW OF MOTION WHEN A BODY (A) EXERTS A FORCE ON A SECOND BODY (B), THE SECOND BODY (B) EXERTS A FORCE EQUAL IN MAGNITUDE, BUT OPPOSITE IN DIRECTION ON THE FIRST BODY (A) FORCES WORK IN PAIRS – NEWTON’S THIRD LAW OF MOTION
FORCE, MOMENTUM AND IMPULSE ANALYSE THE SCIENTIFIC CORRECTNESS OF THE FOLLOWING STATEMENT ABOUT A HORSE PULLING A CART: “WHEN A HORSE PULLS A CART, THE CART PULLS THE HORSE WITH AN EQUAL BUT OPPOSITE FORCE, …….. CONSEQUENTLY THE FORCES CANCEL EACH OTHER OUT AND THE CART IS UNABLE TO MOVE” FORCES WORK IN PAIRS
“… WHEN A HORSE PULLS A CART, THE CART PULLS THE HORSE WITH AN EQUAL BUT OPPOSITE FORCE, …” • ACCORDING TO NEWTON’S THIRD LAW THIS PART OF THE • STATEMENT TRUE!!!!!!!! • THE CART PULLS THE HORSE WITH AN EQUAL BUT OPPOSITE • FORCE THAN WHAT THE HORSE IS PULLING THE CART. • CONSEQUENTLY THE FORCES CANCEL EACH OTHER OUT AND THE CART IS UNABLE TO MOVE” • THIS PART OF THE STATEMENT IS NOT TRUE!!!!!!!!!!!! • THE TWO FORCES ACT ON DIFFERENT OBJECTS AND CAN • THEREFOR NOT CANCEL EACH OTHER OUT. • ONLY THE FORCES THAT ACT IN ON THE CART – • 1 APPLIED FORCE OF THE HORSE • FRICTION OF CART • WILL DETEMINE IF THE CART WILL MOVE. FORCE, MOMENTUM AND IMPULSE FORCES WORK IN PAIRS
• THE TWO FORCES WORK SIMULTANEOUSLY AND HAVE THE SAME MAGNITUDE • THE TWO FORCES HAVE OPPOSITE DIRECTIONS • THE TWO FORCES ARE THE SAME - BOTH FRICTIONAL OR NORMAL FORCES • IF TWO FORCES ACT ON DIFFERENT OBJECTS AND CAN THEREFORE NOT CANCEL EACH OTHER OUT • ONLY FORCES ACTING ON THE SAME OBJECT CAN CANCEL EACH OTHER OUT FORCE, MOMENTUM AND IMPULSE UNDERSTANDING OF NEWTON’S THIRD LAW OF MOTION
FORCE, MOMENTUM AND IMPULSE WHAT IS LINEAR MOMENTUM? LINEAR MOMENTUM (MOMENTUM IN A STRAIGHT LINE) CAN BE DEFINED AS THE PRODUCT OF MASS AND VELOCITY
FORCE, MOMENTUM AND IMPULSE CHANGE IN MOMENTUM A NET FORCE ON AN OBJECT CAUSES A CHANGE IN MOMENTUM - A TACKLE IN RUGBY CHANGES THE MOMENTUM OF THE OPPONENT
FORCE, MOMENTUM AND IMPULSE NEWTONS SECOND LAW OF MOTION IN TERMS OF MOMENTUM THE NET (OR RESULTANT) FORCE EXERTED ON AN OBJECT IS EQUAL TO THE RATE OF CHANGE OF MOMENTUM
FORCE, MOMENTUM AND IMPULSE THROWING AN EGG TO STOP THE EGG, THE MOMENTUM OF THE EGG MUST BE CHANGED TO ZERO THE CONTACT TIME IS THE ONLY SOLUTION TO ENSURE THAT THE EGG EXPERIENCE AS SMALL A FORCE AS POSSIBLE CHANGE IN MOMENTUM
FORCE, MOMENTUM AND IMPULSE CHANGE IN MOMENTUM CATCH A WATER BALLOON TO STOP THE WATER BALLOON, THE MOMENTUM MUST BE CHANGED TO ZERO THE CONTACT TIME IS THE ONLY SOLUTION TO ENSURE THAT BALLOON EXPERIENCE AS SMALL A FORCE A POSSIBLE
FORCE, MOMENTUM AND IMPULSE CHANGE IN MOMENTUM CRICKET PLAYER CATCHING A BALL THE CONTACT TIME IS THE ONLY SOLUTION TO ENSURE THAT CRICKET PLAYER EXPERIENCE A SMALL FORCE
FORCE, MOMENTUM AND IMPULSE CHANGE IN MOMENTUM A BATSMAN HITTING A CRICKET BALL THE MAGNITUDE OF THE NET FORCE, AS WELL AS THE CONTACT TIME , WILL THE DETERMINE THE SUCCESS OF THE SHOT
FORCE, MOMENTUM AND IMPULSE IMPULSE THE PRODUCT OF THE NET FORCE AND THE CONTACT TIME IS CALLED THE IMPULSE (N.s) OF THE FORCE
FORCE, MOMENTUM AND IMPULSE THE CONCEPT OF IMPULSE AND SAFETY CONSIDERATIONS IN EVERYDAY LIFE AIRBAGS AIRBAGS INCREASES THE CONTACT TIME AND THE PASSENGER EXPERIENCE A SMALLER FORCE
FORCE, MOMENTUM AND IMPULSE THE CONCEPT OF IMPULSE AND SAFETY CONSIDERATIONS IN EVERYDAY LIFE CRUMPLE ZONES CRUMPLE ZONES INCREASES THE CONTACT TIME AND THE PASSENGER EXPERIENCE A SMALLER FORCE
FORCE, MOMENTUM AND IMPULSE THE CONCEPT OF IMPULSE AND SAFETY CONSIDERATIONS IN EVERYDAY LIFE ARRESTOR BEDS ARRESTER BEDS INCREASES THE CONTACT TIME FOR A RUNAWAY TRUCK TO BE STOPPED
WHEN DOES MOMENTUM CHANGE? MOMENTUM CHANGES WHEN A NET FORCE ACTS ON AN OBJECT! WHEN IS MOMENTUM CONSERVED? WHEN THE NET FORCE THAT ACTS ON AN OBJECT IS ZERO, THE OBJECT DOES NOT EXPERIENCE AN ACCELERATION THEREFOR NO CHANGE IN VELOCITY. CONSERVATION OF MOMENTUM
CONSERVATION OF MOMENTUM • THE CONTACT TIME DURING WHICH THE FORCES ACT ON THE TWO VEHICLES IS/ARE THE SAME • THE VEHICLES EXPERIENCE THE SAME IMPULSE BUT IN OPPOSITE DIRECTIONS FA = -FB and tA= tB • FAtA = -FBtB • FAtA + FBtB = 0
CONSERVATION OF MOMENTUM THE TOTAL LINEAR MOMENTUM IN A CLOSED SYSTEM IS CONSERVED IN MAGNITUDE AND DIRECTION
CONSERVATION OF MOMENTUM THE TOTAL LINEAR MOMENTUM IN A CLOSED SYSTEM IS CONSERVED IN MAGNITUDE AND DIRECTION
ELASTIC AND INELASTIC COLLISIONS COLLISIONS ARE OFTEN CLASSIFIED ACCORDING TO THE CHANGE IN TOTAL KINETIC ENERGY ELASTIC COLLISIONS TOTAL KINETIC ENERGY OF THE SYSTEM BEFORE THE COLLISION IS EQUALTO THE TOTAL KINETIC ENERGY AFTER THE COLLISION INELASTIC COLLISIONS TOTAL KINETIC ENERGY OF THE SYSTEM IS NOT THE SAMEBEFORE AND AFTER THE COLLISION
ELASTIC AND INELASTIC COLLISIONS TOTAL KINETIC ENERGY BEFORE A COLLISION = TOTAL KINETIC ENERGY AFTER A COLLISION \ EkBEFORE COLLISION = EkAFTER COLLISION \ ½ mv2 = ½ mv2 ELASTIC COLLISIONS
ELASTIC AND INELASTIC COLLISIONS ELASTIC COLLISIONS NEWTON’S CRADLE TOTAL KINETIC ENERGY BEFORE A COLLISION = TOTAL KINETIC ENERGY AFTER A COLLISION
ELASTIC AND INELASTIC COLLISIONS MOMENTUM WILL ALWAYS BE CONSERVED DURING COLLISIONS KINETIC ENERGY WILL ONLY BE CONSERVED DURING ELASTIC COLLISIONS SUMMARY