When we have a body subject to the action of forces with a non-zero resultant, the body can acquire both rotational movement and translational movement, this occurring at the same time. Therefore, we can define the moment of strength as being a quantity associated with the fact that a force causes a body (or object) to rotate.
Let's consider the figure above, where the object is subject to the action of two forces. Point P in the figure is called the pole and was determined at random. we define moment of strength with respect to a pole as being the product of the force (in modulus, that is, considering the positive value regardless of whether the object rotates clockwise or counterclockwise) by the distance between the pole and the point of application of the force (or line of action of the force applied).
The adopted sign is associated with the moment of each force in order to identify whether the force causes a rotation (rotation) in the body, clockwise or counterclockwise. Thus, based on the figure above, we see that F's line of action
1 is at a distance of1 of the pole and the line of action of F2 is at a distance of2 of the pole. We define the moment of the F forces1 and F2 in the following way:M1=+F1.d1 in2=-F2.d2
In the situation described, we use the positive sign for the tendency of the object to rotate in the direction counterclockwise and the minus sign is used to represent that the object tends to rotate in the direction schedule. In the International System of Units, the unit of measure that characterizes the moment of strength is newton x meter (N.m).
F – newton (N)
d – meter (m)
M – newton x meter – N.m
resulting moment
The resulting moment with respect to a given pole is equal to the algebraic sum of the moments of all forces applied to the object, with respect to the same pole.
MR = MF1+ MF2+⋯+ MNF
By Domitiano Marques
Graduated in Physics
Source: Brazil School - https://brasilescola.uol.com.br/fisica/momento-uma-forca.htm
