2A. GRAVITY= The FORCE of ATTRACTION between ANY two objectsAll matter (anything that has mass) has gravity…but it’s only noticeable between massive objects (like planets…)
3Ex: Earth vs. moon Mass of the objects The size of this gravitational force depends on 2 factors:Mass of the objects1. __________________________*As mass increases, the force of gravity increasesEx: Earth vs. moon
4Distance between the objects 2. _________________________________*As distance between the two objects _________, the force of gravity _________.increasesdecreasesThis is why we’re stuck to the surface of the Earth instead of being pulled off towards the more-massive sun.
5The moon has about a 70% effect on our tides. The sun has a 30% effect The moon has about a 70% effect on our tides. The sun has a 30% effect. The sun’s gravity is stronger (179x stronger than the moon), but it’s far away.
7The rotation (spinning) of the Earth creates the equatorial “bulge” The Earth’s diameter at the equator is 27 miles more than the pole to pole diameterSo at the poles you are closer to the center of the earth, so you weigh slightly more.
8Law of Universal Gravitation All objects in the universe attract each other through the force of gravity.
10Acceleration of free-falling objects VELOCITY1. All falling objects accelerate (change ____________) towards the _________ of the Earth due to __________CENTERGRAVITYthe acceleration of a falling object due to gravity (on Earth) =9.8 m/s2 or 9.8 m/s/s
11This means that the velocity of a freely-falling object __________ by ____ m/s for every _______ that passes (up to a certain point…)9.8INCREASESSECONDBut…on Earth, not all falling objects hit the ground at the same time because of _____________ or _______________.air resistanceFLUID FRICTION
13On the moon…all objects hit the surface at the SAME time because there is no ____ on the moon. There IS GRAVITY. Gravity = ____ of Earth.AIR1/6Moon = 1.63 m/s/s
14C. Terminal Velocity -shape -size -weight The __________ speed that an object can have in freefall due to ___________________.MAXIMUMAIR RESISTANCETerminal velocity changes depending on the object’s-shape-size-weight
15As objects fall, _____________ increases until it balances the _______ of the object FLUID FRICTIONWEIGHTTherefore, a heavier object will accelerate for a _________ time period and have a __________ terminal velocity.GREATERGREATER
16A flat sheet of paper falls slowly because of air resistance -it reaches its TERMINAL VELOCITY right away.WeightAirResistanceIf placed on a magazine, the paper accelerates with the magazine. Since the magazine weighs more, it accelerates for a longer time period.
17“DROPPED FROM A HIGH POINT…” GolfBallPingpongBallA ping pong ball reaches its terminal velocity firstA golf ball continues to accelerate for a greater time period and has a greater terminal velocity- so it hits the ground first.DragWeight
19FALLING CATS-There are cats on record that have survived falls of over 32 stories (~320 feet).-They are more likely to die in falls less than 5 stories. HOW IS THIS POSSIBLE?-On average, cats reach their terminal velocity (60 mph) after falling about 5 stories.- Once reaching this velocity, they relax and spread out like a parachute, minimizing injuries.
20D. Projectile Motion: CURVED Motion that has two components (horizontal & vertical) that combine to form a __________ pathCURVEDThe two motions DO NOT affect each other
27E. Weight vs. Mass1. MASSThe amount of _________ in an object that _______ changes. Measured in ___MATTERNEVERkg2. WEIGHTThe gravitational ________ that an object experiences because of its _______.FORCEMASSVaries (changes) by location
28Weight is a FORCE. F = ______________ Mass x accelerationMass= 60kgMass= 60kg
29Homework: KIM vocabulary strategy using the following terms: weight massfree fallterminal velocityprojectile motion