BRIGHT RIDERS DUBAI
JUNE 21, 2025
THREE LAWS OF MOTION
SUBMITTED BY:
VIKRAM
SUBMITTED TO: MS ANU THOMAS
MADHU (9A)
NEWTON’S FIRST LAW OF MOTION
DEFINITION:
NEWTON’S FIRST LAW OF MOTION: AN OBJECT AT REST STAYS AT REST, AND AN OBJECT IN MOTION STAYS IN MOTION WITH THE SAME SPEED AND DIRECTION UNLESS ACTED UPON BY AN EXTERNAL FORCE THIS TENDANCY IS CALLED AS INTERTIA INERTIA CAN BE OF TWO TYPES INERTIA OF REST AND INERTIA OF MOTION
INERTIA OF REST:
THIS TYPE OF INERTIA REFERS TO THE TENDENCY OF AN OBJECT TO REMAIN AT REST UNLESS ACTED UPON BY AN EXTERNAL FORCE OBJECTS DO NOT MOVE ON THEIR OWN THEY NEED A PUSH OR PULL TO START MOVING FOR EXAMPLE, IF A BALL IS LYING STILL ON THE GROUND, IT WILL STAY IN THAT POSITION UNLESS SOMEONE KICKS IT OR ANOTHER FORCE MOVES IT THIS IS BECAUSE THE BALL RESISTS ANY CHANGE FROM ITS STATE OF REST DUE TO ITS INERTIA
INERTIA OF MOTION:
INERTIA OF MOTION IS THE TENDENCY OF A MOVING OBJECT TO CONTINUE MOVING WITH THE SAME SPEED AND IN THE SAME DIRECTION UNLESS A FORCE CAUSES IT TO CHANGE AN OBJECT IN MOTION DOES NOT STOP OR SLOW DOWN BY ITSELF FOR EXAMPLE, IF YOU’RE RIDING A BICYCLE AND SUDDENLY STOP PEDALING, THE BIKE KEEPS MOVING FORWARD FOR A WHILE BEFORE FRICTION AND AIR RESISTANCE GRADUALLY BRING IT TO A STOP THIS HAPPENS BECAUSE THE MOVING BICYCLE WANTS TO KEEP GOING IN THE SAME DIRECTION DUE TO ITS INERTIA OF MOTION
THIS IMAGE SHOWS A SOCCER BALL LYING MOTIONLESS ON THE GROUND. THE BALL REMAINS STILL AND DOES NOT MOVE ON ITS OWN BECAUSE THERE IS NO EXTERNAL FORCE ACTING ON IT THIS BEHAVIOR IS EXPLAINED BY NEWTON’S FIRST LAW OF MOTION, ALSO KNOWN AS THE LAW OF INERTIA ACCORDING TO THIS LAW, AN OBJECT AT REST WILL REMAIN AT REST, AND AN OBJECT IN MOTION WILL CONTINUE MOVING IN A STRAIGHT LINE AT A CONSTANT SPEED UNLESS ACTED UPON BY AN EXTERNAL FORCE IN THE CASE OF THE SOCCER BALL, IT STAYS STATIONARY BECAUSE NO FORCE IS BEING APPLIED TO CHANGE ITS STATE HOWEVER, WHEN SOMEONE KICKS THE BALL WITH THEIR FOOT, THEY APPLY AN EXTERNAL FORCE THIS FORCE OVERCOMES THE BALL’S INERTIA AND CAUSES IT TO START MOVING. THE BALL’S MOTION AFTER THE KICK CLEARLY DEMONSTRATES HOW MOTION BEGINS ONLY WHEN A FORCE ACTS ON AN OBJECT THIS EXAMPLE HELPS US UNDERSTAND THAT WITHOUT AN EXTERNAL FORCE, OBJECTS DO NOT CHANGE THEIR STATE OF REST OR MOTION
IN THIS PICTURE, WE SEE A SKATEBOARDER GLIDING SMOOTHLY ALONG A FLAT, EVEN ROAD. THE SKATEBOARDER CONTINUES TO MOVE FORWARD WITHOUT NEEDING TO CONSTANTLY PUSH OFF THE GROUND THIS ONGOING MOTION HAPPENS BECAUSE THERE IS VERY LITTLE RESISTANCE, AND NO STRONG FORCE IS ACTING TO STOP THE SKATEBOARDER IMMEDIATELY ACCORDING TO NEWTON’S FIRST LAW OF MOTION, ALSO CALLED THE LAW OF INERTIA, AN OBJECT IN MOTION WILL REMAIN IN MOTION AT A CONSTANT SPEED AND IN A STRAIGHT LINE UNLESS ACTED UPON BY AN EXTERNAL FORCE IN THIS CASE, THE SKATEBOARDER WILL KEEP MOVING FORWARD UNLESS A FORCE SUCH AS FRICTION FROM THE GROUND, AIR RESISTANCE, OR AN OBSTACLE LIKE A ROCK OR A CURB ACTS TO SLOW THEM DOWN OR STOP THEM COMPLETELY THIS SITUATION CLEARLY DEMONSTRATES NEWTON’S FIRST LAW BECAUSE THE SKATEBOARDER'S MOVEMENT ONLY CHANGES WHEN AN OUTSIDE FORCE INTERFERES WITHOUT THESE FORCES, THEY WOULD KEEP MOVING IN THE SAME DIRECTION WITHOUT STOPPING THIS LAW HELPS EXPLAIN WHY MOTION CONTINUES UNLESS SOMETHING CAUSES IT TO CHANGE.
NEWTON’S SECOND LAW OF MOTION
DEFINITION:
NEWTON’S SECOND LAW OF MOTION IS ONE OF THE MOST IMPORTANT PRINCIPLES IN PHYSICS. IT EXPLAINS HOW THE MOTION OF AN OBJECT CHANGES WHEN A FORCE IS APPLIED TO IT THE LAW STATES THAT THE ACCELERATION OF AN OBJECT DEPENDS DIRECTLY ON THE FORCE APPLIED AND INVERSELY ON ITS MASS IN SIMPLE TERMS, THIS MEANS THAT AN OBJECT WILL ACCELERATE MORE IF A GREATER FORCE IS APPLIED, AND IT WILL ACCELERATE LESS IF IT HAS MORE MASS (HEAVIER) THE LAW IS MATHEMATICALLY WRITTEN AS:
F = MA
WHERE:
F STANDS FOR FORCE (MEASURED IN NEWTONS, N) M IS THE MASS OF THE OBJECT (MEASURED IN KILOGRAMS, KG) A IS THE ACCELERATION PRODUCED (MEASURED IN METERS PER SECOND SQUARED, M/S²)
WHAT THIS MEANS:
IF YOU APPLY THE SAME FORCE TO TWO OBJECTS OF DIFFERENT MASSES, THE LIGHTER OBJECT WILL ACCELERATE MORE THAN THE HEAVIER ONE FOR EXAMPLE, IF YOU PUSH BOTH A SMALL TOY CAR AND A BIG TRUCK WITH THE SAME FORCE, THE TOY CAR WILL MOVE FASTER BECAUSE IT HAS LESS MASS THE TRUCK WILL MOVE MUCH SLOWER OR MIGHT NOT MOVE AT ALL UNLESS A MUCH GREATER FORCE IS APPLIED.
IMAGE EXPLANATION-1
IN THE IMAGE, WE SEE A PERSON PUSHING TWO SHOPPING CARTS ONE IS EMPTY, AND THE OTHER IS FULL OF GROCERIES WHEN THE SAME AMOUNT OF FORCE IS APPLIED TO BOTH CARTS, THE EMPTY CART MOVES AND SPEEDS UP MUCH FASTER THAN THE FULL ONE THIS HAPPENS BECAUSE THE EMPTY CART HAS LESS MASS, MAKING IT EASIER TO ACCELERATE ON THE OTHER HAND, THE FULL CART HAS MORE MASS, WHICH MAKES IT HARDER TO PUSH AND CAUSES IT TO ACCELERATE MORE SLOWLY. THIS SITUATION CLEARLY DEMONSTRATES NEWTON’S SECOND LAW OF MOTION, WHICH STATES THAT THE ACCELERATION OF AN OBJECT DEPENDS ON ITS MASS AND THE FORCE APPLIED TO IT THE LAW IS EXPRESSED WITH THE FORMULA F = MA, WHERE F IS THE FORCE, M IS THE MASS, AND A IS THE ACCELERATION IF THE FORCE REMAINS THE SAME, THE OBJECT WITH LESS MASS (THE EMPTY CART) WILL HAVE A GREATER ACCELERATION, AND THE ONE WITH MORE MASS (THE FULL CART) WILL HAVE A SMALLER ACCELERATION
IMAGE EXPLANATION-2
THIS IMAGE SHOWS A CAR SPEEDING UP AS THE DRIVER PRESSES THE ACCELERATOR THE ENGINE APPLIES MORE FORCE, CAUSING THE CAR TO MOVE FASTER THE LAW F = MA EXPLAINS THAT IF YOU INCREASE THE FORCE, ACCELERATION ALSO INCREASES (IF MASS STAYS THE SAME) THAT’S EXACTLY WHAT WE SEE IN THIS PICTURE
NEWTON’S THIRD LAW OF MOTION
DEFINITION:
NEWTON’S THIRD LAW OF MOTION STATES THAT FOR EVERY ACTION, THERE IS AN EQUAL AND OPPOSITE REACTION THIS MEANS THAT WHENEVER ONE OBJECT APPLIES A FORCE ON ANOTHER OBJECT, THE SECOND OBJECT ALSO APPLIES A FORCE OF THE SAME STRENGTH BUT IN THE OPPOSITE DIRECTION ON THE FIRST OBJECT. THESE FORCES ALWAYS OCCUR IN PAIRS AND ACT ON TWO DIFFERENT OBJECTS FOR EXAMPLE, WHEN WE WALK, OUR FOOT PUSHES BACKWARD ON THE GROUND (ACTION), AND THE GROUND PUSHES OUR FOOT FORWARD (REACTION), HELPING US MOVE ANOTHER EXAMPLE IS A ROCKET LAUNCHING THE ROCKET PUSHES GASES DOWNWARD, AND THE GASES PUSH THE ROCKET UPWARD WITH EQUAL FORCE. THESE ACTION AND REACTION FORCES DO NOT CANCEL EACH OTHER BECAUSE THEY ACT ON DIFFERENT BODIES THIS LAW HELPS US UNDERSTAND HOW MOTION HAPPENS IN MANY EVERYDAY SITUATIONS
WHAT THIS MEANS:
NEWTON'S THIRD LAW OF MOTION, STATES THAT FOR EVERY ACTION, THERE IS AN EQUAL AND OPPOSITE REACTION THIS MEANS THAT WHEN ONE OBJECT EXERTS A FORCE ON ANOTHER OBJECT, THE SECOND OBJECT EXERTS A FORCE BACK ON THE FIRST THAT IS EQUAL IN MAGNITUDE BUT OPPOSITE IN DIRECTION. IN SIMPLER TERMS, WHEN ONE OBJECT EXERTS A FORCE ON ANOTHER OBJECT, THE SECOND OBJECT EXERTS A FORCE BACK ON THE FIRST THAT IS EQUAL IN STRENGTH BUT OPPOSITE IN DIRECTION.
KEY POINTS ABOUT NEWTON'S THIRD LAW:
ACTION AND REACTION FORCES:
THE FORCES INVOLVED ARE CALLED ACTION AND REACTION FORCES, AND THEY ALWAYS OCCUR IN PAIRS EQUAL MAGNITUDE:
THE MAGNITUDES OF THE ACTION AND REACTION FORCES ARE ALWAYS THE SAME
OPPOSITE DIRECTION: THE DIRECTIONS OF THE ACTION AND REACTION FORCES ARE ALWAYS OPPOSITE TO EACH OTHER.
ACTING ON DIFFERENT OBJECTS: THE ACTION AND REACTION FORCES ACT ON DIFFERENT OBJECTS, NOT THE SAME OBJECT
IMAGE EXPLANATION-1
WHEN SOMEONE JUMPS OFF A BOAT, THE BOAT MOVES BACKWARD IN THE OPPOSITE DIRECTION. THIS HAPPENS BECAUSE OF NEWTON’S THIRD LAW OF MOTION, WHICH STATES THAT FOR EVERY ACTION, THERE IS AN EQUAL AND OPPOSITE REACTION IN THIS CASE, THE ACTION IS THE PERSON PUSHING AGAINST THE BOAT TO JUMP FORWARD AT THE SAME TIME, THE REACTION IS THE BOAT BEING PUSHED BACKWARD WITH AN EQUAL FORCE. SINCE THE PERSON AND THE BOAT ARE IN CONTACT, THE FORCE APPLIED BY THE FEET ON THE BOAT ALSO CAUSES THE BOAT TO MOVE IN THE OPPOSITE DIRECTION THE LIGHTER THE PERSON AND THE HEAVIER THE BOAT, THE LESS THE BOAT WILL MOVE BUT THE FORCES REMAIN EQUAL AND OPPOSITE THIS SIMPLE EXAMPLE CLEARLY SHOWS HOW MOTION HAPPENS DUE TO ACTION AND REACTION FORCE PAIRS.
IMAGE EXPLANATION-2
AS THE ROCKET ENGINES FIRE, THEY PUSH HOT GASES RAPIDLY DOWNWARD OUT OF THE NOZZLES THIS DOWNWARD FORCE ON THE GASES IS THE ACTION FORCE IN RESPONSE, ACCORDING TO NEWTON’S THIRD LAW OF MOTION, THE GASES EXERT AN EQUAL AND OPPOSITE REACTION FORCE ON THE ROCKET, PUSHING IT UPWARD THIS REACTION FORCE LIFTS THE ROCKET OFF THE GROUND AND PROPELS IT INTO THE SKY. EVEN THOUGH THE ROCKET IS VERY HEAVY, THE FORCE FROM THE HIGH-SPEED GASES IS STRONG ENOUGH TO OVERCOME GRAVITY THIS POWERFUL EXAMPLE CLEARLY DEMONSTRATES NEWTON’S THIRD LAW THAT FOR EVERY ACTION, THERE IS AN EQUAL AND OPPOSITE REACTION THE ROCKET WOULDN’T MOVE UPWARD UNLESS IT PUSHED SOMETHING ELSE (THE GASES) IN THE OPPOSITE DIRECTION. THIS PRINCIPLE IS THE BASIC IDEA BEHIND HOW ROCKETS, JET ENGINES, AND EVEN SPACE TRAVEL WORK