Dr. Marina El Maraghy
Density
Dr. Marina El Maraghy
Dr. Marina El Maraghy
What is density?
❖ Density is the mass of the substance per unit volume.
❖ Units:
Kg/m³
and
g/cm³
Practice:
A box has a mass of 200 g and a volume of 50 cm3.
Calculate the density.
Density= Mass/Volume= 200/50= 4 g/cm3
Floating and Sinking??
Why does a cork floats while a piece of iron sinks??
Why does oils floats and honey sinks??
ITS BECAUSE OF DENSITY 😉
A lower density substance floats over the higher density.
Dr. Marina El Maraghy
Dr. Marina El Maraghy
Relation between Density with mass and volume:
❖ Let’s think together ….
❖ What happens to the density if the mass increases??
At a constant volume, as the mass of an object increases the density increase.
Constant
❖ What happens to the density if the volume increases??
At a constant mass, as the volume increases the density decreases.
Constant
THIS MENS THAT
Density is directly proportional with mass at constant volume.
Density is inversely proportional with volume at constant mass.
Dr. Marina El Maraghy
Dr. Marina El Maraghy
Experiments:
A) Experiment to calculate the density of a liquid:
1) To get the volume of the liquid use a measuring cylinder.
2) To get the mass of the liquid first weigh the measuring cylinder alone
and name it M1.
3) Then weigh the measuring cylinder filled with the liquid and name it M2.
4) Then subtract both readings M2 – M1 to get the mass of the liquid.
5) Then calculate the density by dividing mass with the volume.
To get the volume
Dr. Marina El Maraghy
To get the mass
Dr. Marina El Maraghy
B) Experiment to calculate the density of an irregular solid:
1) Measure the mass of the irregular solid using a balance.
2) Get an empty measuring cylinder and pour some water in it.
3) Record the volume from the measuring cylinder and name it V1.
4) Put the irregular solid inside the measuring cylinder and record the
second volume and name it V2.
5) Then subtract both volumes V2 – V1 to get the volume of the solid.
6) Then calculate the density of the solid by dividing mass with volume
To get the Volume= V2 – V1
To get the mass: Use a balance
Dr. Marina El Maraghy