Most often, we refer to mass as “weight,” but technically there is a difference between the two.  Martial artists may find it interesting to know the distinction, since it is mass (not weight) that is a component in the formula for Force, which martial artists strive to increase in their delivery of Taekwon-Do attacks and blocks.

Mass is defined as the amount of matter an object has. One of the qualities of mass is that it has inertia.  As an example of inertia, imagine an ice puck resting on a frozen pond. It takes a certain amount of force to set the puck in motion. The greater the mass, the more force will be needed to move the puck. The same is true if the puck were sliding along the ice. It would continue to slide until a force is applied to stop the puck. The more massive the puck is, the more force will be needed to stop the motion of the puck. Mass is a measure of how much inertia an object shows.

The weight of an object on earth depends on the force of attraction (gravity) between the object and earth.  

Weight is what you get when you have a mass in a gravitational field.  The more massive something is, the more it will weigh in a gravitational field.  Since most of us spend our entire lives in the earth’s gravitational field, people often confuse weight and mass.