NEWTON’S LAWS

NEWTON’S FIRST LAW CLICK HERE FOR A SHORT VIDEO

AN OBJECT IN MOTION STAYS IN MOTION Unless another force acts upon it This rider hasn’t had a stopping force act on him…. YET

NEWTON’S 1 ST IN DIFFERENT WORDS

SO IF YOU THROW A BALL, WHY DOESN’T IT JUST GO ON AND ON INTO OUTER SPACE FOREVER? Friction forces occur as it passes through the air, causing it to slow down Simultaneously, gravity forces are pulling it down to Earth Once it hits land, friction with the ground eventually causes it to stop. If you threw it while in space where there is no friction or strong gravity source nearby, it WOULD keep going on forever

NEWTON’S SECOND LAW CLICK HERE FOR A SHORT VIDEO Force = mass x acceleration

BECAUSE THIS PLANE HAS SUCH A HUGE MASS, THIS MAN’S FORCE WON’T BE ABLE TO ACCELERATE IT MUCH

THE GREATER THE FORCE, THE MORE THE OBJECT CAN ACCELERATE

More mass= less acceleration Less mass= more acceleration

PRACTICE PROBLEMS Force= Newtons Mass= kilograms Acceleration= m/ sec 2 (meters per second squared which means meters per second every second)

PRACTICE PROBLEM What net force is required to accelerate a car at a rate of 2 m/s 2 if the car has a mass of 3,000 kg? ?= 3000 X 2 FORCE = 6000 Newtons

NOW HALF THE MASS—HOW DOES IT AFFECT THE FORCE? What net force is required to accelerate a car at a rate of 2 m/s 2 if the car has a mass of 1500 kg? ?= 1500 X 2 FORCE = 3000 Newtons

PRACTICE PROBLEMS An automobile with a mass of 1000 kilograms accelerates when the traffic light turns green. If the net force on the car is 4000 Newtons, what is the car’s acceleration? 4000 = 1000 x ? 4 meters per second squared

NOW DOUBLE THE CAR MASS An automobile with a mass of 2000 kilograms accelerates when the traffic light turns green. If the net force on the car is 4000 Newtons, what is the car’s acceleration? 4000= 2000 x ? 2 meters per second squared DID YOU SEE HOW THE ACCELERATION WAS CUT IN HALF?

Ronda Rousey’s (an MMA fighter) arm is 4.6 kg. If she punches a guy in the face with an acceleration of 40 meters/second 2, how much force will he feel? What if she doubles her acceleration to 80? m/s 2 ? What if a much bigger man with an arm size of 8 kg throws the exact same punch? Why are there weight classes in boxing and MMA?

NEWTON’S 3 RD LAW CLICK HERE FOR A SHORT VIDEO

FORCES COME IN PAIRS AND ARE OFTEN CALLED “ACTION” AND “REACTION”

THEY ALWAYS EQUAL EACH OTHER

Now, lightly push against the side of your table with your pinky finger only. Now, push hard enough with your pinky to try to move the table. Did you notice that the table pushed you back harder the second time? What would happen if you pushed against a concrete wall with just one pinky… I mean push with ALL YOUR WEIGHT AND STRENGTH. How hard would the wall push back? It is likely that the force would be so great that you could break your pinky finger

THESE FORCE PAIRS ARE ALWAYS OPPOSITE IN DIRECTION

Though they are equal, they can create movement This is because the forces are each acting on different objects