Transcript Gravity- I`m Attracted to You

GravityI’m Attracted to You
S8P5. Students will recognize characteristics of
gravity, electricity, and magnetism as major
kinds of forces acting in nature.
a. Recognize that every object exerts gravitational
force on every other object and that the force exerted
depends on how much mass the objects have and how
far apart they are. (DOK 1)
Gravity
force of attraction that exists between
all matter in the universe.
► The
 Key word is matter
 Matter is the stuff you are and everything else
is made of
► It
takes a lot of mass for the gravity to be
noticeable.
 Like planetary mass
Law of Gravity
► The
force of attraction between any two
objects depends on their masses and the
distances between them.
 The bigger the object, the more gravity it has
 The closer an object is to something the
stronger the pull.
Mass
is how much matter is in something.
► It is measured using grams and kilograms
► It is NOT the same as weight
► Mass
Distance
► Gravity’s
force depends on how close the
object is to something.
► As an object gets further away, the force of
gravity on that object decreases
► Inverse square law
 As the distance increases the gravity decreases
exponentially
► Class
demonstration
1
Gravitational force =
Distance squared
G force =
1
d2
Weight, Mass, and Gravity
►Weight
and Mass are not
the same thing!!!
► The
are related though
► Weight is your mass being pulled down by
gravity
► Gravity on earth pulls us down at 9.8 m/s2
Weight, Mass, and Gravity
Mass
► How much matter you
are made of
► Does not change
depending location
► It is the same if you
are on earth or in
space or on the moon
Weight
► The relationship
between mass and
gravity
► Changes depending on
location
► Is different on earth
and the moon and
space
► In
the absence of air resistance, all things
will fall toward the earth at the same
velocity
► Weight = mass x free-fall acceleration
► w= m g
Find Your Mass
► We
can find out how much mass we have by using
the previous formula
►W
= mg
► Weight is in Newtons, so convert your lbs to N.
 Multiply lbs times 4.448
► Then
divide by gravity
Gravity on Earth
► Gravity
pulls us down toward the center of
the earth.
► At different parts of the earth there is more
matter between the surface and the center.
► The Poles are flatter and the equator bulges
 The bulge means there is more gravity at the
equator
 People weigh more at the equator than the
poles.
Gravity & the Moon


Newton observed the Moon’s motion and
realized that its direction changes because of
the gravitational attraction of Earth
 The Moon is constantly falling toward Earth
 If no gravity, the Moon would continue to
move in a straight line and would not orbit
Earth
The same is true of the planets and their
moons, stars, and all orbiting bodies
throughout the universe.