Physics

Unit 3 Lab 1 Density and Archimedes Principle

Buoyancy 1.05 (colorado.edu)

Solids and Metals - Specific Gravity (farm.net)

Name: Click or tap here to enter text.

Open the simulation: https://phet.colorado.edu/sims/density-and-buoyancy/buoyancy_en.html See link on Canvas.

Part 1 Mass and Weight Density

Using the Intro tab of the simulation, find the mass, weight, and volume of each object (Block of Wood and brick). The mass is printed on each object. Use the scale above water for the weight. Figure out how you can get the volume.

The water level measures the volume below the water line in liters (L).

1 L = 1,000 cm3

1 m3 = 1,000 L

Convert your volume into cubic meters before recording the volume.

Object	Mass	Weight	Volume	Mass Density	Weight Density
Wood
Brick

Be sure to add your units to the header or after each number.

Convert your values for Weight Density to the English Units of pounds/cubic foot.

Some useful conversion factors:

1 lb = 4.45 N = is the weight of 0.454 kg of mass

1 kg of mass weighs 2.2 lbs = 9.8 N

1 m3 = 35.3 ft3.

Object	Weight Density lb/ft3
Wood
Brick

Part 2 Archimedes Principle

Rerecord the mass and weight of the brick in the table below and then add the “submerged weight” of the brick. Use the weight above water and the weight submerged to calculate the buoyant force on the brick.

Object	Normal Weight	Submerged Weight	Buoyant Force
Brick

Remember to include units.

Calculate the specific gravity of the brick using the formula:

Object	Specific Gravity
Brick

Change the liquid from water to oil and reweigh the brick under oil.

You should be able to answer the following question based on your measurements. Remember the difference between the scale readings above and below the liquid indicates the weight of the displaced liquid.

The density of oil is _____________ the density of water.
	a	less than
	b	the same as
	c	greater than

Put an “X” in the yellow cell to the left of your choice.

Part 3 Archimedes Principle with Real Weights and Scales

Take turns measuring the weight of two objects provided by the instructor on a Newton weight scale. Your instructor will identify which weight is object 1 and which is object 2.

After using the scale, find the mass in grams of each object and convert to kilograms. Then calculate the weight using the formula Weight = mass x gravity, using gravity = 9.8 N/m.

Then weigh each object on the scale when the object is submerged in water.

Record the weight and use the data to calculate the specific gravity of each object. Then consult the list of densities to suggest which material the object might be.

Object	Mass, g	Mass, kg	Weight, N	Submerged scale	Specific Gravity	Likely Material
Object 1
Object 2

The list of densities is on the next page. If you don’t find a good match, check the Internet of a table of specific gravities. The following link might help:

http://www.farm.net/~mason/materials/specific-gravity.html