Measurement and Density
The objective is to (1) become familiar with measurement devices commonly used in scientific work, and (2) measure the mass densities of a few selected objects.
A dial caliper, a micrometer, a mass balance, a few regularly shaped solids, and a scientific calculator
Measuring instruments have limited precisions that must be considered during use. These limited precisions will result in the transmission and compounding of errors. Observing the use of appropriate number of significant figures is important in obtaining a result that can be trusted to a certain degree. The student should have an understanding of significant figures prior to this experiment. Click on Significant Figures for a review.
Mass density is defined as the mass per unit volume. gm/cm3 is, therefore, a unit of mass density. The mass density of an object may be found by dividing its mass by its volume.
Formulas used in the calculation of volume (V) are:
Rectangular block or cube: V = length x width x height = lwh.
Sphere: V = (4/3) π R3.
Cylinder: V = π R2l.
Mass densities of a few substances are given below:
|Aluminum 2.7 gm/cm3||Ice 0.9 gm/cm3||Brass 8.6 gm/cm3|
|Concrete 2.3 gm/cm3||Iron 7.8 gm/cm3||Lead 11.3 gm/cm3|
|Copper 8.9 gm/cm3||Steel 7.8 gm/cm3||Gold 19.3 gm/cm3|
Given: The accepted values for the densities of the metals used. (See Table 1).
I) Aluminum rectangular block (Use a Dial caliper):
|Trial||Length (cm)||Width (cm)||Thickness (cm)||Mass (gram)|
II. II) Steel sphere (use a micrometer):
|Trial||Diameter (cm)||Mass (gram)|
Comparison of the results:
Provide the percent error formula used as well as the calculation of the percent errors.
State your conclusions of the experiment.
Last Updated: Dec. 02, 2014