Gases & Liquids: Buoyancy
Discover a technique, Archimedes Principle, for easily determining the buoyant force on an object submerged in a fluid. Then use Archimedes Principle to predict whether an object will float or sink.
Students tabulate data based on known samples, then use the information to extrapolate the behavior of the unknown.
Lab Summary
Students will use two Force Sensors to discover the relationship between the buoyant force on various incompressible, nonabsorbent objects immersed in water and the weight of the water displaced.
They will discover that a floating object is supported by a buoyant force equal to the object's weight and use this knowledge to predict whether a new object will float or sink.
Theory
An object immersed in a fluid is buoyed up by a force equal to the weight of the fluid being displaced. Using the force sensor readings before and after an object is immersed, this force is easily calculated. This also creates an easy way to measure the density of the fluid and predict whether objects of a given density will float or sink.
Downloads
- Computer-based lab (PDF, 756 KB) (755 KB, .pdf)
(student version)
- Xplorer GLX-based lab (PDF, 1.7 MB) (1.67 MB, .pdf)
(student version)
Method
Use a Force Sensor to measure the buoyant force on a fully submerged object. Measure the weight of the displaced water. Compare the buoyant force to the weight of the displaced water.
Here's What You Need
U.S. Educator prices shown.
Probeware
PASPORT Force Sensor (PS-2104) - $110
Designed to measure both pulling and pushing forces. Uses range from collisions to tug-of-war. For use with PASPORT Interfaces.
Xplorer GLX (PS-2002) - $349
The Xplorer GLX is a data collection, graphing, and analysis tool designed for science students and educators.
Other Products
Density Set (ME-8569) - $75
Investigate density by Archimedes' principle of displacement, specific heats and basic length/volume relationships.
Overflow Can (SE-8568) - $15
Provides direct volume measurements for materials that displace the liquid for buoyancy experiments.
Large Rod Base (ME-8735) - $89
A sturdy, general-purpose base can support one or two rods, and is ideal for experiment setups that require extra stability.
Right Angle Clamp (SE-9444) - $16
This clamp fits rods up to 18 mm (11/16 in) in diameter.
Lab Jack-Small (10x10) (SE-9374) - $110
Raise, support and align equipment with this wide-based Small Laboratory Jack.
Braided Physics String (SE-8050) - $22
This string is tough, resists stretching, and will not unravel. Provides 320 meters of string.
Other Materials
- Plastic Beaker with lipped rim, 250 mL
- Beaker or cup, 250 mL
- Graduated Cylinder, 50 mL
- Ruler
- Paper Cup, Small (3 oz.)
- Water, Room Temperature
- Liquid Detergent or Soap
- Paper Towels
- Masking Tape
Lab Manual
The computer-based activity is included in Explorations in Physics (PS-2810). The Xplorer GLX-based lab is included in Physics with the Xplorer GLX (PS-2826). Both manuals are complete with Teacher Information pages, student instructions and handouts, and sample data.
For your convenience, we offer bundles which provide the probeware for the
activities in the manual. For more, please see:
Computer-based
Physics Lab Manual and Bundles
Xplorer
GLX-based Physics Lab Manual and Bundles
