Measurement of mass
Mass is a property of matter. It does not depend on temperature, pressure and location of the body in space. Mass of a body is defined as the quantity of matter contained in a body. The SI unit of mass is kilogram (kg). The masses of objects which we shall study in this course vary over a wide range. These may vary from a tiny mass of electron (9.11×10−31kg) to the huge mass of the known universe (=1055 kg). The order of masses of various objects is shown in Table 1.6.
Ordinarily, the mass of an object is determined in kilograms using a common balance like the one used in a grocery shop. For measuring larger masses like
Table 1.6 Range of masses
| Object | Order of mass (kg) |
|---|---|
| Electron | \(10^{-30}\) |
| Proton or Neutron | \(10^{-27}\) |
| Uranium atom | \(10^{-25}\) |
| Red blood corpuscle | \(10^{-14}\) |
| A cell | \(10^{-10}\) |
| Dust particle | \(10^{-9}\) |
| Raindrop | \(10^{-6}\) |
| Mosquito | \(10^{-5}\) |
| Grape | \(10^{-3}\) |
| Frog | \(10^{-1}\) |
| Human | \(10^{2}\) |
| Car | \(10^{3}\) |
| Ship | \(10^{5}\) |
| Moon | \(10^{23}\) |
| Earth | \(10^{25}\) |
| Sun | \(10^{30}\) |
| Milky way | \(10^{41}\) |
| Observable Universe | \(10^{55}\) |
that of planets, stars etc., we make use of gravitational methods. For measurement of small masses of atomic/subatomic particles etc., we make use of a mass spectrograph.
Some of the weighing balances commonly used are common balance, spring balance, electronic balance, etc.