Archimedes' Principle Lab: Measuring Buoyant Forces, Study notes of Experimental Physics

Download Archimedes' Principle Lab: Measuring Buoyant Forces and more Study notes Experimental Physics in PDF only on Docsity! Experiment 12 Archimedes’ Principle Fig. 12-1 Equipment Triple Beam balance Wood cylinder 2 Metal cylinders String Graduated cylinder Pipette Vernier caliper Rod & Clamp Overflow container Advance Reading: Serway & Jewett - Chapter 14, Section 14-4 Objective: The objective of this lab is to measure the buoyant force on a number of objects. Theory: Archimedes’ principle states that a body wholly or partially submerged in a fluid is buoyed up by a force equal in magnitude to the weight of the fluid displaced by the body. It is important to remember that fluid includes liquids and gases. This force is given by: FB = ρVg (Eq 1) where ρ (rho) is the density of the fluid, V is the volume of fluid displaced and g is acceleration due to gravity. It is the buoyant force that keeps ships afloat in water and hot air balloons floating in air. In this experiment, the buoyant force will be measured three ways and the results compared. The first method is by the measurement of force. This method involves weighing an object first in air, then in water, and using the difference in weight as the buoyant force. Though the object's mass does not change, its apparent weight will change when measured while immersed in a fluid that is denser than air. The second method is the displaced volume method. The volume of fluid displaced by the object is measured and its weight calculated. The weight of the water displaced is equal to the buoyant force exerted on the object, by Archimedes' Principle. The third method is by the buoyant force equation method. By measuring the dimensions of the object and calculating the volume, one can determine the buoyant force (by using Εq-1) that would be exerted on the object when it is submerged in a fluid of known density ρ . Please note that for the third method, the volumes of interest are different for objects that float and objects that sink. Procedure Part 1: Force Measurement method- Weight 1. Measure the mass of one of the metal cylinders in air and calculate its weight. Label this weight in air FA. Suspend the object by a string tied to the pan of the Triple-Beam balance. Partially fill the overflow can with water, then completely submerge the cylinder. Do not allow the cylinder to touch the sides of the container. Measure its “mass” while it is submerged. Calculate its weight in water, Fw. The difference between the object’s weight in air and its weight in water is the buoyant force on the object, or F B = F A ! F B (Eq 2) Experiment 12 Archimedes’ Principle