Background:  Archimedes Principle states that when an object is submerged under water, the object loses weight equal to the weight of the water it displaces.  By performing a series of demonstrations using the Archimedes’ Blocks, a better understanding of the Archimedes’ Principle and such related concepts as density, weight, mass displacement and buoyancy can be gained.

Materials:
1000 mL beaker,   water,   string,   Archimedes block,   Spring scale,   5 g & 10 g masses

Description of block:  The block is a hollow  cube-shaped structure with a top that snaps  open and shut. There is a loop screwed into  the top of the block so that it can be  suspended from a piece of string.  The block  is designed so that it can be submerged in water;  the snap top prevents water from entering  the block when it is submerged.  On the outside of the block there is a grid of  1 cm2 squares; these grid marks make it easy  to measure how far the block has sunk in a  container of water (or solutions of different  densities).  The block has a square base that measures  5.0cm by 5.0cm  The height of the block,  including the top, is 4.0 cm.  Thus, the block  has a total volume of 100 cm3 .  The bottom of the block is slight thicker  than the walls and the top.  This gives the  block a lower center of mass.  The thick bottom  acts as a ballast to anchor down or stabilize the  block when floating in water.

 
 
The block, including its top, masses 25 g without
any contents, giving the block a density of __________ show the calculation below

Density of the empty block =

The density of water is 1.0 g / cm³  Determine the ratio of density of block to water.
 
 

How much of the block will float above water?
 
 

What percentage will be submerged below water?
 
 
 
 
 
 
 

Displacement and Buoyancy

Archimedes’ Principle states that when an object is submerged under water, it loses weight
equal to the weight of water it displaces.  To demonstrate this, add 85 g of mass to the empty block.

Write out the information

 Mass of block  +         Added masses       =         total mass
 
 _____________       ____________          ____________
 

Next, thread a piece of string through the loop at the top of the block and suspend the block
from a spring scale.
At this point, the reading on the spring scale reads_____________grams

Next, completely submerge the block in the container of water.
The block displaces _________  mL of water which is equal to its entire volume.

Since 100 mL of water has a mass of 100 grams, the block has an apparent weight of only __________ grams.

                Total mass       -           Buoyant force                        =        Apparent weight of block under water
                                            (mass of water displaced)

                _______ g         -            _________  g                      =        ___________ g
 

Now, add additional masses so that the block contains 100 g of weights, for a total mass of 125 grams.
Repeat the above  procedure suspending the block. from the spring scale, and then submerging the block
in the container of water.  Again, the 100 grams of the total mass of the block will be buoyed up by water

scale should register an apparent weight of  _____ grams

Show your work.  Remember the block will displaces its own volume of 100 mL of water every time it is submerged
therefore; its apparent weight under water is always ___  grams  more OR less the total mass of the block
                                   (circle  one)

                Total mass       -           Buoyant force                        =          Apparent weight of block under water
                                            (mass of water displaced)

                _______ g         -            _________  g                      =       ___________ g
 
 

What would happen if we changed the liquid from water to alcohol whose density is 0.8 g/ml?
What would happen if we changed the liquid to Epsom salt solution with a density of 1.2 g/mL?
 

On a separate sheet of paper write a general statement as to the affect of each (alcohol and Epsom Salt)\
the above 2 total masses - 110grams and 125 grams.  And then prove by calculating the apparent weight
of each using the same masses.  Set up your paper with your name, period, date on the top of the paper.
On the title line write the name of the lab.

Solution of alcohol
    Explanation:
    Calculation to prove explanation
                0.8g/mL    =    mass/100mL   (the mass you determine is the mass of displaced alcohol)

                Total mass       -           Buoyant force                        =        Apparent weight of block under water
                                            (mass of alcohol displaced)

                _______ g         -            _________  g                      =           ___________ g
 

Solution of Epsom salt
    Explanation:
    Calculation to prove explanation
                1.2 g/mL    =    mass/100mL   (the mass you determine is the mass of displaced Epsom Salt solution)

                Total mass       -           Buoyant force                        =        Apparent weight of block under salt solution
                                     (mass of Epsom salt solution displaced)

                _______ g         -            _________  g                      =             ___________ g