Calculating and measuring the densities of different objects, (effects of density)Copy

Learning Objectives

• Recall and use the equation ρ = m / V
• Describe an experiment to determine the density of a liquid and of a regularly shaped solid and make the necessary calculation
• Describe the determination of the density of an irregularly shaped solid by the method of displacement
• Predict whether an object will float based on density data

Contents to learn

Density
Density of a substance is defined as “the mass of substance per unit volume”.

Density = Mass / Volume

The S.I unit of density is kg/m3 or g/cm3

Mass of the substance can be found by using common level balance. Volume of a substance can either be found by calculation from linear measurements or by usning measuring cylinder.

Density of water = 1 g / cm3 = 1000 kg / m3

Determination of density (Regular shaped objects)
By measuring the dimentions of regular shaped object we can detremine the its volume by using mathematical formula.

Volume = Length X Width X Height

By using balance we can find mass of the object.

Putting the values of mass and volume in the following formula, we can detrmine the density of the regular shaped object

Density = mass / volume

Determination of density (Irregular shaped objects)
To determine the density of irregular shaped objects, we use displacement method to calculate the volume of the iregular shaped object.

Use the balance to find the mass (m) of object choose the measuring cylinder that will accept the object.add liquid to the cylinder to fill it enough,so that the object will be completely submerged.measure volume v1 of liquid.

Lower the object into liquid and measure the new reading V2 so volume of object is

V=V1-V2

Density = mass ( m ) / volume ( V )

This method can only be used for the objects having densities greater than density of water.

Density of different materials
Density of different materials are as under.