# Relative Density Laboratory Report

Experiment 6: Relative Density Laboratory Report Jessica Manansala, Nathaniel Martinez, Maria Pacia, Jeanelle Pedrigal, Miguel Poblete Department of Math and Physics College of Science, University of Santo Tomas Espana, Manila Philippines Abstract The experiment would introduce us to 3 concepts, namely, the definition of relative density, the Archimedes principle and the determination of density by the Archimedes principle.

In the first activity, we were tasked with finding the density of a cylinder of a known metal; this was done by submersing the cylinder of metal in a measured amount of water and calculating the displaced water against the measured mass of the cylinder. The next activity required us to compute for the density of a given bone. The bone was first weighed, submersed in water and then weighed again. After which the relative density was then computed. The third activity required us to measure the weights of diet and regular soft drinks and then compute for their density. Introduction

Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity usually means relative density with respect to water. The term “relative density” is often preferred in modern scientific usage. If a substance’s relative density is less than one then it is less dense than the reference; if greater than 1 then it is denser than the reference. If the relative density is exactly 1 then the densities are equal; that is, equal volumes of the two substances have the same mass.

If the reference material is water then a substance with a relative density (or specific gravity) less than 1 will float in water. For example, an ice cube, with a relative density of about 0. 91, will float. A substance with a relative density greater than 1 will sink. [1] Archimedes’ principle relates buoyancy to displacement. It is named after its discoverer, Archimedes of Syracuse. Archimedes’ treatise, On floating bodies, proposition 5 states: Any floating object displaces its own weight of fluid. â€” Archimedes of Syracuse

For more general objects, floating and sunken, and in gases as well as liquids (i. e. a fluid), Archimedes’ principle may be stated thus in terms of forces: Any object, wholly or partially immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object. â€” Archimedes of Syracuse With the clarifications that for a sunken object the volume of displaced fluid is the volume of the object, and for a floating object on a liquid, the weight of the displaced liquid is the weight of the object. More tersely: buoyancy = weight of displaced fluid. [2]