How does the volume of a
completely submerged
object compare with the
volume of water displaced?
They are the same
What is the mass of 1 liter of
water in kilograms? What is
its weight in newtons?
1 kg
10 N
When the buoyant force on a
submerged object is less than
the weight of the object, how
do the densities of the object
and water compare?
The density of the object is
greater then the density of
water.
The buoyant force is always
equal to the ______________.
For the special case of floating
the buoyant force is also equal
to the ________________.
The buoyant force is always
equal to the weight of the fluid
displaced.
For the special case of floating
the buoyant force is also equal
to the weight of the floating
object.
A 1 kg block of iron and a 1 kg
block of aluminum are
submerged in water. Upon
which does the greater
buoyant force act?
More on the aluminum because
the volume is greater.
Find the Buoyant Force and the Net force
for each of the three scenarios below.
A)BF= 7N Net Force = 0N
B)BF = 10N Net Force = 80N
down
C)BF= 10N Net Force = 3N up
A block of wood with the
dimensions of 2.5 cm x 1.0 cm
x 6.5 cm has a density of 0.8
g/cm3. What is the buoyant
force on this block of wood
when it is floating in water?
0.13 N
• If all the taconite falls out of one of the
ships on Lake Superior will the water level
of Lake Superior rise, fall or remain the
same? WHY?
• If instead, the ship was filled with
Styrofoam and then it all went overboard –
will the water level rise, fall or remain the
same? WHY?
• Fall. When in the ship the taconites mass
is being displaced and when it sinks only
its volume is being displaced in the lake.
Taconite is more dense than water so its
mass is greater than its volume.
• Stay the same – in both cases the
Styrofoam floats.
How does the waterline of this ship
change when it is loaded with 55,500
metric tons of iron ore. (there are
1000 kg in one metric ton). The ship
is 306 m long and 32 m wide.
Waterline changes by 5.7
meters!