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Force Buoyancy Lab

Force Buoyancy Lab

Purpose:

In this activity you will be learning the factors that affect the force of buoyancy on an object in a fluid.

Information:

  • Your force buoyancy will be equal to the difference between the weight of your object in air and the "apparent weight" of your object in a fluid.

  • Setup


  • Forces.  Give a picture and the equations for the bottle underwater.


Procedure

Part 1:  Force Buoyancy vs. Acceleration due to gravity

  1. Open the program found here and set the fluid to Gasoline.

  2. Make sure you start your experiment on the Earth with a volume of 500 mL and a mass of 1000 grams.  If you have to, reload the program and these three values will be the presets.  Just don't forget to set the fluid to gasoline.

  3. Start the first trial and allow the 16 seconds to elapse and then get a reading for the force when it was in the air and the force when it was in the fluid.  Subtract these forces to get the force of buoyancy.


  4. Repeat on each of the other bodies available to you in this program.  Do not make changes to any other parameter.

  5. Make a graph of Force Buoyancy vs. ag.  Make sure you get the equation of this graph and put a nice copy of your equation and the graph into your lab book.

Part 2:  Force Buoyancy vs. Fluid Density

  1. Open the program found here and set the fluid to Gasoline.

  2. Make sure you start your experiment on the Earth with a volume of 100 mL and a mass of 2000 grams. 

  3. Start the first trial and allow the 16 seconds to elapse and then get a reading for the force when it was in the air and the force when it was in the fluid.  Subtract these forces to get the force of buoyancy.



  4. Repeat on each of the other fluids available to you in this program.  Do not make changes to any other parameter.

  5. Make a graph of Force Buoyancy vs. density.  Make sure you get the equation of this graph and put a nice copy of your equation and the graph into your lab book.

Part 3:  Force Buoyancy vs. Bottle Volume

  1. Open the program found here and set the fluid to Maple Syrup.

  2. Make sure you start your experiment on the Earth with a volume of 600 mL and a mass of 1000 grams. 

  3. Start the first trial and allow the 16 seconds to elapse and then get a reading for the force when it was in the air and the force when it was in the fluid.  Subtract these forces to get the force of buoyancy.

  4. Repeat with 7 more volumes (total of 8).  Do not make changes to any other parameter.

  5. Make a graph of Force Buoyancy vs. volume.  Make sure you get the equation of this graph and put a nice copy of your equation and the graph into your lab book.

Part 4:  Force Buoyancy vs. Mass (Live Part)

  1. In this part of the lab you will only be collecting data for one mass and you will be sharing your data with the rest of the class.  The extra credit for this lab will be awarded to all members of the class that gets the best data.

  2. Before you collect your data, set up your data table to look like the one pictured below and allow for enough data rows for each group in your class.



  3. Use a triple beam balance to measure the mass of the container that you get from your teacher.

  4. Set the force probe to 10 N and hook it to channel 1.

  5. Open Logger Pro and go to the "Experiment" menu and select "Data Collection".  Set your data collection duration for 30 seconds.

  6. Zero your force probe while holding it vertically.

  7. Begin collecting data with nothing on the force probe, then hook on your container and allow it to hang freely in air.  Finally, fully submerge the container in water and don't allow it to touch the sides or bottom of the bucket.  Your force graph should look like the one pictured below:



  8. Highlight the portion of the graph where the container is in air and find the average value of the force.  This will be equal to force gravity.

  9. Highlight the portion of the graph where the container is in water and find the average value of the force.  This will be equal to force tension when in water.

  10. Put your bottle letter, mass, and two forces on the board for the other groups in your class to copy.

  11. Dry off your container and put all your materials back where you got them from.

  12. Record the data for all the other groups and then subtract your force tension in water from your force gravity.  This will be equal to your force buoyancy.

  13. Graph the force buoyancy (y) vs. the mass of the containers (x).  Do NOT autoscale your graph but instead double click on your graph to bring up the graph options and then click on the axes options tab.   Change the y and x axes to manual scale and make sure y minimum is zero, and y maximum is 8.  Make sure x minimum is zero and x maximum is 800.


Things to have in your lab book:

  • Purpose

  • Information

  • A picture of the lab set up and a picture of the forces on the bottle when it is under water.

  • Data tables (one for each part)

  • Graphs for each part with equations and/or constants

  • A statement of conclusion for each part.

  • A few possible sources of error and suggestions on how to minimize them.
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