Materials that Float and Sink

Marie Jaja T. Roa Santa Maria West Central School Schools Division of Ilocos Sur
Lesson 1

I have here two different kinds of
balls. Which ball do you think
will float and which will sink?

Sink means to go below the surface of the water.
Float means to stay above the surface of the water.

Have you ever
wondered why
some object sinks on
water, while some
object floats?

Float
Sink
Descriptive
words for
objects that
float and
objects that
sink.

Rocks in a river.
Ice in a drink.
Some things float.
Some things sink.
Floating things
have buoyancy
Test a little
toy and see
Does it sink?
Does it float?
Could you use it
as a boat?
Try a pencil.
It pop up.
Try a hammer.
Try a cup.

Test some objects
in your bath.
Watch them.
Now you’re
doing Math
If something
is denser than the water
it will sink
But if the water’s
denser, then…
Well,
What do you think?
©Amy LV

Well, it’s all
about something
called density.
What causes objects to
sink and float?
Density is the degree of
compactness as of an object.

Everything is made of molecules.
Molecules are tiny particles
that can be seen with a
microscope.

Tightly packed molecules
in an object
Loosely packed
molecules in an object

Objects with tightly packed molecules will sink if it is
more dense than the liquid it is immersed in.

Objects with loosely
packed molecules will
float if it’s less dense
than the liquid it is
placed in.

REMEMBER: Materials with a
density less than that of a liquid
float and materials with a greater
density than the liquid sink.

Does the shape of an object
affects its ability to float?

Changing the objects shape will also make its
ability to float because it holds air and
upthrusts has more space to push the object.

Upthrust is the force that pushes an object up
and makes it seem to lose weight in a liquid.
It is a push that always goes straight UP,
against the direction of gravity.

Upthrust is the force which is responsible in
making an object float or sink in a liquid.

Imagine trying to hold this beach ball and this
tennis ball, under the water. Which would be
easier to hold underwater? Why?

REMEMBER:
Shape affects upthrust. The larger
the surface area of an object, the
stronger the upthrust.

Factors Affecting
Sinking or Floating
of Objects
Density or
compactness of
an object
The
material
it is
made of
Weight of
an object
Shape or
form of
an object
Type of
liquid

Float means to stay above the surface of the
water.
Sink means to go below the surface of the water.
Buoyancy is the tendency of an object to float in
liquid.
Density is the degree of compactness of an object.
Upthrust is the force that pushes an object up in a
liquid.

Materials that Float and Sink

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