24DQ - University Physics with Modern Physics

Question

Why is it incorrect to say that 1.0 kg equals 2.2 lb?

Step-by-Step Solution

Answer

Kg is the unit of mass (SI unit system), whereas lb is the unit of force/weight (British unit system).

Step 1: Mass and Weight

In everyday life, mass and weight are interchangeably used, which is incorrect. Mass is a measure of how much inertia the object has. An object having a larger mass will have larger inertial, i.e., larger resistance to change in its motion.

Whereas on the other hand, weight is the gravitational force on the object by the earth. Mass is always constant, but the weight will depend on the value of acceleration due to gravity which differs from one planet to planet.

Step 2: Kilogram kg and pound lb

Kg is the unit of mass (SI unit system), whereas lb is the unit of force/weight (British unit system). 

Hence the statement 1.0 kg equals 2.2 lb is incorrect.