Density of a substance is the mass per unit volume of the substance. For example to find the density of a body, you find a ration of the mass of the body to the volume of that body.
Density = M/V
where M is mass, V is volume
------ Methods of Determining Density
Direct methods: Here the mass and volume of the body is measured directly. Used for solid shapes with regular shapes.
Indirect Methods: Here the mass may be weighed directly or indirectly, but the volume is usually determined indirectly. Eg the volume of an irregular shaped object may be determined by displacement method, that is the object is immersed into a beaker of water and the volume of displaced liquid is equivalent to the volume of the object.
A glass block of length 10cm, width 8cm and thickness 2cm has a mass of 400g. Calculate the density of the glass.
Density = Mass/Volume
mass = 400g
volume = lxwxh = 10 x 8 x 2 = 160cm
density = 400/160
soyode bolutifeThis is good but I need more emphasis on density...looking at the change of units...this example given is easy and most examiners,they kinda confuse the students...they don't give such questions where they are staight forward. Some require the change of units maybe from g to Kg but you didn't give me enough examples where the application of this is used. 0007 October 2011
soyode bolutifeThank you as you reply...:) 0007 October 2011
andy chuks@soyode, if you are given to show your answer in kg/m^3
Eg on the above if you should show your answer in kg/m^3, firstly convert 400g to kg i.e 400/1000 = 0.4kg then convert 10cm, 8cm 2cm to metres i.e 10/100 = 0.1m, 8/100 = 0.08, 2/100 = 0.02m respectively
The volume = lxwxh = 0.1 x 0.08 x 0.02 = 0.00016m^3
Therefore: Density = m/v = 0.4/0.00016 = 25000kg/m^3 1008 October 2011