Mass Measurements

Matter is anything that has mass and occupies space. Mass refers to the amount of matter
inside the object. Hence, mass is referring to the amount of matter packed in the object.
Mass does not vary with pressure and temperature. The SI unit for mass is the kilogram (kg)
which is made of platinum iridium cylinder kept in France. Mass can be measured using
balances - double and triple beam balances

    
BEAM BALANCE                                                     TRIPLE BEAM BALANCE

  DOUBLE BEAM BALANCE

Method of Reading: 

Beam Balance: 

• Check that the beam balance is calibrated (pointer at the zero mark when the pans at the ends are balanced.) correctly. 

• Object whose mass is to be determined is placed at one end. 

• Standard masses are then placed on the other pan to balance the beam. When the beam is balanced, the masses ale added up to give the mass of the object. 

In double and triple beam balances, there is only 1 pan. 

• The masses are attached to the beam which can be slide along. 

• The masses are adjusted along the beam until the pointer comes to rest at the zero mark. 

Electronic balance: 

• More sensitive and accurate (can be up to 0.01 g) 

• Reading in digital form. 

Weight Measurements

 

Weight is defined as the pull of gravity on the mass.Weight varies from place to place, depending on the force of gravity.  

 

Weight is measured in Newton (N) 

Newton = Force (Gravitational force) x Mass (kg)  

Can you point out 2 differences between Mass and Weight? 

 

Weight can be measured using the force meter or newton meter as shown on the right. 

Density Measurements

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

Object is denser if it has a greater amount of matter packed into the same volume compared to that of another object. 

 

Density =  Mass (divide) Volume 

SI unit : kg/m3

  

Relative Density

• 

Relative density of a substance is defined as the density of that substance divided by 

the density of pure water. 

• 

Water is the standard used to compare materials with. 

• 

Objects with relative densities greater than 1.0 will sink whilst those with less than 1 

will float. 

Density of pure water at 4°C is 1.0 g/cm3.

Physical measurements for relative densities, the standard of measuring relative densities is fixed to 4°C.