Objective:

To develop a theory about how weight/mass, volume and type of material affect density.

Introduction:

Scales usually measure one of two things: mass or weight. Mass is the amount of matter, and weight is the reaction of a mass to gravity. Mass is usually stable, changing only if material is added or subtracted. Weight, however, depends on which forces are acting on the mass. Weight varies with height, to the point where objects can be weightless! Also, other forces besides gravity can affect a measurement meant to indicate an object's weight.

The purpose of this experiment is to understand the meaning and significance of the density of a substance and buoyant force. Density is a basic physical property of a homogeneous substance; it is an intensive property, which means it depends only on the substance's composition and does not vary with size or amount. The determination of density is a nondestructive physical process for distinguishing one substance from another. Density = mass/ volume

Archimedes Principle The buoyant force, FB on an object is equal to the weight of the fluid it displaces when it is submerged in the fluid. Here buoyant force FB = density x volume x gravity

When there is no overflow, buoyant force FB is found from difference between weight in air and weight while submerged in liquid.

Apparatus:

• This lab will be completed using online simulation. Use the following link to access the simulation. If you do not have Flash Player installed, it might not run. Rerun the simulation after you install Flash player.

http://www.thephysicsaviary.com/Physics/Programs/Labs/ForceBuoyancy/index.html

1. Force Buoyant vs. Acceleration due to gravity
2. Click on 'Begin'. Click on 'Fluid' until it changes to 'Gasoline'.
3. On open program, select: 'Earth', 'Bottle Volume of 500mL' and Mass of '1,000' grams.
4. Click on 'Start' and allow enough time for bottle to be completely submerged and motionless. Graph shows total time as sixteen seconds.
5. Obtain from your graph values for force in air and force when submerged in fluid. Subtract these forces to get buoyant force.
6. Click on 'Location' to change. Repeat procedure for all other locations available in this simulation. Leave all other parameters unchanged except location. Record data in table below.
7. Make a graph of Force Buoyancy vs. Gravity. Calculate Slope of best fit line.

Planet	g (m/s2)	Force in Air (N)	Force in Fluid (N)	Force Buoyancy (N)
Earth	9.8
Moon	1.62
Mars	3.71
Venus	8.87
Jupiter	24.79
Vesta	0.22

1. Force Buoyant vs. Fluid Density
2. Click 'Reset' on the lower right of simulation screen. Select fluid as 'Gasoline'.
3. Select location as 'Earth', Bottle Volume as 100mL, mass as 2,000 grams.
4. Start first trial and allow 16 seconds to elapse before you read values off graph. As in previous run, subtract reading of force when in fluid from force when in air to determine buoyant force.
5. Click on 'Fluid' to change fluid. Do not change any other parameter. Now repeat experiment for all available fluids in simulation. (e) Record data in table below
6. Make a graph of Force Buoyant vs. Density. Calculate slope of best fit line.

Planet	Density (kg/m3)	Force in Air (N)	Force in Fluid (N)	Force Buoyancy (N)
Gasoline	737
Maple Syrup	1333
Crude Oil	825
Fresh Water	1000
Mercury	13,500

1. Force Buoyant vs. Bottle Volume
2. Click 'Reset' on the lower right of simulation screen. Select fluid as 'Fresh Water'.
3. Select location as 'Earth', Bottle Volume is 100mL, mass is 1,000 grams.
4. Click 'Start' and allow 16 seconds to elapse before you read values off graph. As in previous runs, subtract reading of force when in fluid from force when in air to determine buoyant force.
5. Click on 'Bottle Volume' to change volume of bottle. Do not change any other parameter. Now repeat experiment for seven different 'Bottle Volumes' available in simulation.
6. Create a data table and record your experimental data.
7. Plot a graph of Force Buoyant Vs Volume.

Discussion

1. How did the location (different gravity) affect the forces in air, fluid, and buoyancy?
2. How did the type of fluid affect the forces in air, fluid, and buoyancy?
3. Describe the relationship of Force Buoyant and Bottle volume based on your plot you made in #3.
4. How does adequate experimentation help you make accurate prediction?