# Measure of a force

We say that the idea of strength is directly related to the daily experience of any person. Whenever we pull or push an object, we say that we are exerting a force on it. In several of these pulls or pushes we sometimes use a lot of force, although we don’t know how much force we actually apply.

Usually we do not measure such intensity, but when we are going to measure a quantity, we must necessarily choose a unit to carry out the measurement and even to characterize it. As we mentioned earlier, in the case of force, there is a unit that is widely used in everyday practice, which is **1 kilogram-force** , which is represented by the symbol **1 kgf.**

In fact, this unit is nothing more than **weight .**of an object, which we call a standard kilogram. An interesting fact is that the standard kilogram is stored in Paris (France), at the International Bureau of Weights and Measures. Based on this information, we can define that **1 kilogram-force (1kgf) is the force with which the Earth attracts the standard kilogram (that is, its weight) at sea level and at 45º latitude.**

*An observation that we must always make is regarding the specification of the place, it is necessary because the weight of a body varies from one place to another, even if it is almost not noticeable* .

Although it is widely used in everyday life, kgf is not the unit of force in the International System of Units. As we have seen in previous studies, the SI unit of force is called 1 newton = 1 N, in honor of Isaac Newton. The relationship between these two units is:

1kgf = 9.8 N

Or, as can be found in some textbooks, approximately:

1kgf = 10 N

Therefore, the force of 1 N = 0.1 kgf is practically equal to the force that the Earth exerts on a pack of 100 g. The device for measuring force is called a dynamometer. You may already know this device, as it is widely used in popular markets to measure weights of groceries and other objects.