Question

The unit of mass in the SI system is ________ and the unit of weight in the SI system is ________.
A. kg, Newton
B. m, Ampere
C. seconds, Joule
D. ergs, Newton

Answer 1

Hint: We have studied that SI system or international System is the modern form of metric system. This is the world’s most widely used measurement system. This system consists of a set of units together. We know that there are seven base units. Other units are derived from these base seven units.

Complete answer:
The base seven units are meter (length), kilogram (kg), second (time), kelvin (temperature), ampere (electric current), mole (amount of matter in a substance) and candela (intensity of light). So the unit of mass is kilogram in the SI system. Mass of a body is always constant everywhere in the universe whereas the weight of the body varies from place to place and it becomes zero at the centre of earth. Weight can be defined as the force by which the earth attracts towards its centre. It is always directed towards the centre of the earth So it is a vector quantity while mass is scalar quantity. Weight of a body is given by equation, $W = mg$ where $W$ is weight, $m$ is mass of body and $g$ is the acceleration due to gravity of earth. Hence the unit of weight is \[kilogram - meter/se{c^2}\] or Newton. Thus the unit of mass in the SI system is kg and the unit of weight in SI system Newton.

So, the correct answer is “Option A”.

Note:
Hence mass and weight are separated quantities and have different units of measure. We come to know that weight is a force so it has the same unit of force that is newton. The unit of mass is kilogram which is well known as it is used in daily life.