GravityGravity

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Law of Universal Law of Universal Gravitation Gravitation

The force of gravity applies to everything The force of gravity applies to everything in the universein the universe

It can be calculated using the formula:It can be calculated using the formula: F= G(MF= G(M11MM22/d/d22)) G is the constant of universal gravity G is the constant of universal gravity M is the mass of each object M is the mass of each object D is the distance between themD is the distance between them

Properties of GravityProperties of Gravity Gravitational force Gravitational force

increases as mass increases as mass increasesincreases the sun’s gravitational the sun’s gravitational

force is 28 times that of force is 28 times that of that of Earth.that of Earth.

Gravitational force Gravitational force decreases as distance decreases as distance increases increases

Pair sharePair share: A explain to B (using the law of gravity) why the moon orbits the Earth and not the sun.

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Free fallFree fall When gravity is the only force When gravity is the only force

acting on a object the object is the acting on a object the object is the free fallfree fall

The free fall near the Earth’s The free fall near the Earth’s surface is constantsurface is constant 9.8m/s9.8m/s22

Pair sharePair share: B explain to A why both the mouse and elephant hit the ground at the same time.

WeightWeight Weight is equal to mass times free-fall Weight is equal to mass times free-fall

accelerationacceleration Weight = Mass x free-fall acceleration Weight = Mass x free-fall acceleration

(W=mg)(W=mg) Weight is less when gravity is less Weight is less when gravity is less

MERCURY The Same person who

weighs 49 lbs on Mercury

would weigh 307 lbs on

Jupiter

JUPITER

Terminal velocity Terminal velocity Terminal velocity is when air resistance Terminal velocity is when air resistance

and gravity are equaland gravity are equal Air resistance pushes up on falling objectsAir resistance pushes up on falling objects

Free fall and Free fall and motionmotion

Free fall exists only when gravity is the Free fall exists only when gravity is the only force acting on an objectonly force acting on an object

Free fall only occurs in a vacuum Free fall only occurs in a vacuum The earth orbits the sun because of free The earth orbits the sun because of free

fallfall An orbit is when an object moving forward An orbit is when an object moving forward

is also in free fall is also in free fall

Projectile Motion and Projectile Motion and GravityGravity

Projectile motion is the curved path that an Projectile motion is the curved path that an object follows when thrown object follows when thrown The object is moving in two directions at once The object is moving in two directions at once

– forward and down – forward and down The forward motion is a constant velocity, not The forward motion is a constant velocity, not

effected by the downward pull of gravityeffected by the downward pull of gravity

Whiteboard Whiteboard : Would the motion of a ball thrown with the same force on the Earth and moon have the same motion? Explain.

White White board board

Review Review 1)1) As mass increases As mass increases

what happens to what happens to gravitational force?gravitational force?

2)2) What 2 things are What 2 things are need to calculate need to calculate weight?weight?

3)3) Objects have an orbit Objects have an orbit because of their because of their forward motion and forward motion and _____________. _____________.

Summary - Read over Summary - Read over your notes then write your notes then write

In 4 sentences describe the properties In 4 sentences describe the properties of gravity & how they relate to weight of gravity & how they relate to weight & projectile motion. & projectile motion.

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