hello my name is Amy and this is an
experiment regarding Archimedes
principle for physics lab Archimedes
principle basically states that the
buoyant force applied to an object is
equal to the weight of the fluid the
object displaces an object moves the
fluid so can occupy the volume the fluid
originally occupied the buoyancy force
is the force applied upward on an object
by any fluid so basically we have two
cups here with the exact same amount of
liquid which is about 3/4 cup and I'm
going to add 20 milliliters of ice to
this cup and they're kind of cut smaller
so as you can see the water level rose
originally it's kind of like below the
blue line a little now it rose up to
there and I'm also going to add in this
cup a block of ice same amount with a
nail inside there's the nail if you can
see it and it's kind of sinking because
the nail is more toward the bottom of
the ice cube okay so the basic
calculations that go into this
experiment and I'll put this over here
so we can see as the ice melts that we
can predict that the one with the ice
cube the water level is going to stay
the same and the one with the nail in
the ice that the water level is actually
going to go down so we have this idea
that the buoyant force is the weight of
displaced water so the point force is
equal to the mass of the water and the
gravitational force is equal to the
density of water times the volume of the
water displaced also
gravitational force so the mass of the
water is the density of the water times
the volume of the water displaced so the
weight of the ice cube is the mass of
the ice times the gravitational force is
equal to the density of the ice times
the volume of the ice times the
gravitational force but since the ice
cube is floating the buoyant force is
equal to the weight setting the equation
here equal to each other and then
rearranging it you can solve for the
volume of the water displaced by the ice
cube which is this ok so this is the
volume of the water that Ice Cube
displaced so what is the volume of the
water that the ice cube adds on once it
melts so since we know that the mass of
the ice cube it's the same as the mass
of the water left after it melts you can
write this that the density of the ice
and the volume of the ice is equal to
the density of the water and the volume
of the water so the total volume is
basically just the density of the ice
times the volume of the ice and the
density of the water which is exactly
the same volume as before so when the
ice cube melts it fills up exactly the
same amount of volume as the water
displaced to hold up the ice cube
because there's a force holding up the
ice cube so the water level it remains
the same ok so now back to our
experiment here it's taking awhile but
you can see here that the ice has you
can see that the ice has pretty much all
melted here and we have an ice cube with
the nail in it which is going to take a
little longer to melt
so the nail has basically fallen out of
the ice and we could see the water level
is a little bit higher but once that ice
cube melts it should get a little lower
um because the density of the nail is
greater than the density of the water
which is greater than density of ice
which is greater than the density of the
air and the volume of the ice that is
submerged under the water before melting
should equal the volume of the water
formed after melting this idea of
displacement by Archimedes the buoyant
force on the ice cube is equal to the
weight of the displaced water so when it
melts the mass of the ice and the mass
of the ice and the water are gonna be
the same
the displaced volume again after the ice
melts is going to be greater than a
volume of the total water and ice so the
water goes down with the nail embedded
and that's because the nail was taking
up space in the ice
and as we know the mass of water is one
gram per centimeter cubed our ice cube
now has just about melted away and
there's our nail at the bottom so as you
can see here with the first cup the
level of waters there stayed the same
after adding that 20 grams of ice in
there and over here 20 grams with the
nail there we go
