Measurement of Mass / Weight

What is Mass?

Mass is the quantity of matter contained in a body. With the System Internationale (S.I) unit, the standard unit of mass is kilogram.

The measurement of the mass of a body is carried out with the aid of chemical balance or beam balance in the laboratory and these instruments can measure up to 0.001 g, which is the reading accuracy of the beam or chemical balance.

The mass of an object is measured by comparing it to a known mass on the arm of the chemical or beam balance. Other instruments that can be used to determine the mass of an object include electronic balance, triple beam balance, lever balance, etc.

What is Weight?

Weight (W) of an object is the gravitational pull of the earth on a body. It is measured with the aid of an instrument known as spring balance and the S.I unit of weight is Newton (N).

The weight of a body varies from place to place on the earth’s surface.

The differences between mass and weight are stated as follows:

Mass vs. Weight:

Relationship Between Mass And Weight:

The formula that connects mass and weight is the relationship between mass and weight. This formula is used in calculations, to either calculate the mass of a given weight of an object or to calculate the weights of a given mass of an object.

The formula is:    

Weight = Mass × Acceleration due to Gravity
Weight = m × g

where m is the mass (in Kg) and g is the acceleration due to gravity (in m/s² or ms^-2).

Example 3.1.1:

Calculate the weight of a mass 350 g. (g = 10 ms^-2 )

Solution:

Values given:

Mass = \( \scriptsize 350g \)

Convert this to kg which is the standard unit

Mass = \( \scriptsize 350\:g \\ = \frac{350}{1000} \\ = \scriptsize 0.350\:kg \)

Formula:

Weight = mass × acceleration due to gravity

W = m × g

Solution:

Weight = 0.350 kg × 10 ms^-2

Weight = 3.5 N