LABORATORY I:

DENSITY, SPECIFIC WEIGHT, AND SPECIFIC GRAVITY

Objective

In this experiment you are introduced to the concepts of density, unit weight, and specific gravity. Many other concepts which are important in Fluid Mechanics such as viscosity, fluid pressure, buoyancy and hydrostatic force, etc., are derived from these three basic concepts. You will determine the specific weight (or unit weight) and density and calculate the specific gravity of various liquids and solid objects. Through simple weight or mass and size or volume measurements you will be able to understand these quantitative properties of the studied materials as well as the interrelationships among these properties.

Data Analysis

1. State all the equations used to calculate ρ, γ, and SG.

2. Tabulate all the raw data collected in the lab. Be sure to label the columns appropriately and include correct units.

3. Determine an average value for every property measured and follow the next steps using only the average values. Calculate ρ, γ, and SG of the fluids and solid materials tested using average values.

4. Identify the unknown fluid by comparing its calculated experimental properties (or measured properties) with tabulated values of ρ and γ (or theoretical properties) for different types of motor oils from your Textbook or other sources.

5. Tabulate your major results and present the Table(s) in the Data Analysis section of your report. In the first Table show your calculated ρ, γ, and SG values for all substances measured in both U.S. Customary and S.I. units.

6. In a second Table compare measured y of water with the value from your textbook at the measured temperature. In the same 'fable, also continue measured γ values of the solid objects (iron and concrete cube) and unknown fluid with theoretical values found in your Textbook or any other source.

7. Show sample calculations (including all steps for finding ρ, γ, and SG starting fmm raw data) for ONE or the fluids or objects measured during this laboratory.

Points to Discuss in the Report

1. How does the temperature of the fluids affect their measured densities?

2. Explain how well your calculated y values match published values for all the substances measured.

3. What assumptions affected the accuracy of this experiment? Note any sources of error in your measurements. When writing this point. make a clear differentiation between assumptions and sources of error.

4. Why is it important to know the density, specific weight, and specific gravity of fluids in hydraulic engineering? Explain.

5. Give at least two specific examples of applications where you will need to know either property (ρ, γ, SG) of the fluids in hydraulic engineering.