GRAVITY The acceleration due to gravity on Earth is 9.8 m/sec 2 (~22 mph/sec) (This means that each second an object falls, it increases its.

GRAVITY

GRAVITY GRAVITY

GRAVITY

•The acceleration due to gravity on Earth is

9.8 m/sec2 (~22 mph/sec)

(This means that each second an object falls, it increases its speed by 9.8 m/sec until itreaches its terminal velocity)

•a force of acceleration that causes objects to become attracted to each other

-based on the object’s mass and distance between them

•Gravity pulls all objects at the same rate.

•Mass does not affect the pull from gravity.

•Weight: How heavy an object is because of gravitational pull

•Mass: Amount of matter in an object

However….

Some objects do fall slower because of

AIR RESISTANCE

-A force that opposes the motion of an object as it moves through air

•highest speed that an object can fall at determined by the object’s shape and mass

Once an object reaches its terminal velocity,it falls at a constant velocity.

(It does not accelerate unless its shape changes.)

TERMINAL VELOCITY

Some objects also fall slower because of their……

Reaches this when the air resistance exerts an upward force exactly equal and opposite to the force of gravity. Heavier mass needs faster falling speed for drag to equal gravity

The elephant hits first because of its mass. It takes more time to reach its terminal velocity.

The feather reaches its terminal velocity very quickly because it has very little mass.

Vacuum: A vacuum is a place that has no matter – thus there is no air (ex: in outer space)

All objects will fall at the same velocityregardless of shape and mass.

If there is no air, there is no air resistance

Tennis ball test

…..but with air resistance and outside factors, the speed should be between 40-50 mph.

A tennis ball’s terminal velocity is about 70 mph.

Other Terminal VelocitiesHuman ~120mphRaindrop ~ 12mph16lb Bowling Ball ~ 163mphBaseball ~ 75mph

HOW WOULD OUR LIVES BE DIFFERENT WITHOUT GRAVITY???

http://www.explorelearning.com/

Sign up for the gravity interactive – off the leaning tower of pisa

Teacherdomain.org

Balloon Car Project due Friday

Poster

Data Tables (re-done on the computer)•Distance•Top Speed•Momentum

Builders Journal (preferred typed)

Terms Sheet (typed)

UPCOMING SCIENCE EVENTS

Mini Project Next Week

Test on Thursday 22nd 1st or 2nd Week in January

Science Placement Test from PV

LET’S REVIEW………..NEWTON’S LAWS

AN OBJECT IN MOTION WILL STAY IN MOTION UNLESS ANOTHER FORCE STOPS IT

AN OBJECT AT REST WILL STAY AT REST UNLESS ANOTHER FORCE STARTS IT

FIRST LAW

SECOND LAW

FORCE = MASS x ACCELERATION

“HEAVIER OBJECTS NEED MORE FORCE TO GET THEM GOING OR TO STOP THEM”

THIRD LAW

EVERY ACTION HAS AN EQUAL AND OPPOSITE REACTION

AIR GOES THIS WAY

CAR GOES THIS WAY

IT WILL NOT MOVE UNTIL YOU GIVE IT A FORCE-IT WON’T STOP UNTIL FRICTION OR A WALL STOPS IT.

YOUR BALLOON CAR WILL EXPERIENCE ALL THREE

THE HEAVIER YOUR CAR IS, THE MORE FORCE IT WILL TAKE TO GET IT GOING

WHEN THE AIR COMES OUT OF THE BALLOON, YOUR CAR WILL GO FORWARD (the opposite way)