Forces and Motion
6th Grade Unit
Becky Berg
What is Gravity?
Gravity is the word we use to describe
the pull between masses.
Things with more
MASS produce a
greater Gravity
pull on each other.
A Little Song About
Gravity
Click on the
music note to
hear the
gravity song!
Gravity controls….
A roller coaster’s ride
A diver’s dive
A skier’s jump
A baseball’s fall
What word describes
how much of you there
is?
I’d eat a looott of
yummy bread to
gain mass!
Mass
Your mass is the amount of
material that your body
contains. How can you gain
mass?
Does something that is
bigger always have
more mass?
Does bigger= more
mass?
So, having more mass
does not mean taking up
more space!
Mass vs. Weight
Do things that have
more mass always
weigh more?
When you stand on a bathroom scale,
the scale is made of springs. The
farther down you push the springs, the
higher the number on the scale. The
number tells you your weight. On earth
it is true that the more mass you have,
the more weight you have.
Weight? Mass?
I am totally
confused!
Pretend That You Are in
Space!
You are floating around.
You drift over to a floating
bathroom scale and put your
feet on it. Your feet do not
push down on the scale at
all. The scale shows that
you weigh 0. You have lost
your weight—but did you
lose your mass?
Oh where, oh where,
has my weight gone?
Oh where, oh where
can it be?
All my body parts are
still together—so I still
have mass!
On a space flight, your
mass would be the
same; but your weight
would change.
Summing up Mass and
Weight
Your MASS is the amount of material in
your body.
Your MASS doesn’t depend on where
you are.
Your WEIGHT is how much your body
pushes down on a scale.
Your WEIGHT depends on how much
MASS you have and where you are.
Where would you weigh
the most?
OR
Earth
Moon
Remember, gravity describes the pull
between masses. You have mass, and
the earth has mass. There is a pull
between you and the earth. We
measure this pull with a scale. The
more the gravity, the greater the
squeeze on the springs of the
scale…and the more you weigh.
Gravity and Weight
Summary
Your weight on earth is a measure of
the GRAVITY pull between you and the
earth. Bodies with more MASS
produce a greater GRAVITY pull on
each other.
On Earth
So, if I ate a lot of
yummy tuna fish
while standing on the
scale, I would gain
mass.
The pull between the
earth and me would
become greater—and I
would weigh more!
Back to the Moon
During my trip to the
moon, my mass does
not change, but the
moon has much less
mass than the earth.
Still on the Moon!
There is less gravity
pull between you and
the moon. If you
stood on the scale on
the moon—you
would weigh less
than on earth!
Imagine…..