Let's try to find out what is called the moment of force. This term is often used in physics. Under the analyzed term is meant the product of the shoulder and the force applied to it.
Features
Analyzing the question of what is called the moment of force, it is necessary to mention the units of measurement of this quantity. In the international SI system, it is measured in Nm.
Rotational moment
The rotational moment of a force relative to a point is the quantity associated with a shoulder and a force. In everyday life, people often use the “rule of leverage”, which is based on the moment of power.
For example, in order to balance the swing scales, you need to know what is called the moment of effort, and how to apply it correctly. The shoulder is the gap between the point of application and the pivot point.
For example, it is problematic to open the door, pushing it at the mounting points. In order to understand why this is so difficult to do, you need to know what is called the moment of force relative to the axis.
Assume that you need to open a door that has a width of a meter, attaching 100 N. to it. You need to apply it in three places:
- near loops;
- in the center;
- at the edge of the canvas.
For the first case, the shoulder will be zero, therefore, the product of the exerted shoulder force will be a zero value.
For the option in the center of the door, the moment will correspond to 50 Nm. For the lower part of the door leaf, the moment will have a maximum value of 100 N · m.
Such calculations allow us to conclude that the loss in distance is compensated by the gain in effort.
Shoulder rule
In the case of applying force at an angle, it is impossible to talk about determining the shoulder forces as it was previously considered. In order to cope with the task, it is necessary to use the shoulder rule. The shoulder of force is the length of the perpendicular, which is omitted from the point of rotation to the line of action of the force.
In order to determine the shoulder strength, you need to lengthen the line. Then a perpendicular is lowered onto it from the rotation point.
The result is a triangle with right angles. Using the rules of trigonometry, it is possible to determine the moment of force through a sine.
Suppose force was applied at an angle of 45 degrees. In this case, the moment is 70 Nm. It becomes obvious that it will not be possible to open the door at an angle of 0 degrees. Such a force does not have a projection capable of causing a rotational motion. The absence of a shoulder other than zero does not allow the force to create torque. Reflecting on what is called the moment of force, it should be noted that this is a vector quantity. In order to determine the direction of the moment of force, use the rule of the right hand. Similarly determine the direction of the angular velocity vector .
What is the peculiarity of such a rule? The axis of rotation is covered with the palm of the right hand so that the direction of the fingers coincides with the direction of the applied force. The thumb determines the direction of the vector of the moment of force. What is called a moment of force with respect to a fixed point? This is the value that connects the projection of the vector of the moment of force and the axis relative to which the calculation will be carried out.
The main moment of forces is called a vector equal to the sum of all the moments of individual forces that act in the system relative to the same point. It is called the center of bringing the entire system of forces.
In general, the result of the action on the solid of any system will be the same as the action of the main moment of the system of forces, as well as the vector of forces applied in the center of reduction.
Conclusion
To describe the moment of forces, the basic law of dynamics, which characterizes the rotational motion, is used. It connects the moment of inertia, angular acceleration, the moment of forces. After the rule of leverage was established by Archimedes, without any transformations it was used for almost 1900 years. Only in the second half of the 17th century did the French scientist P. Varignon change it and was connected with the moment of forces.
If the lever is in equilibrium, the equality M1 = M2 is respected. The moment of force is a characteristic of the rotational action of the force. It depends not only on strength, but also on her shoulder. In order to unscrew the nut, use a long wrench. Screws are unscrewed much faster with a screwdriver having a fairly long handle.