Two force calculation couple

1.

Definition of couple: a pair of parallel forces with equal size, opposite direction but not collinear acting on the same rigid body is called couple. Under the action of concentrated couple, the shear diagram does not change

so choose C

have a good time

2. Wrong
couple
property 1: the couple has no resultant force, so the couple cannot be replaced by a force, nor can it be balanced with a force

explanation:
from the definition of couple and the resultant projection theorem of force, it can be seen that the algebraic sum of the projection of two forces in the couple on any coordinate axis in its action plane is always zero, so the couple has no resultant force, and the couple can only have rotation effect on the object, while a force has two effects of movement and rotation on the object in general. Therefore, the effect of couple and force on the object is different, so it can not be equivalent to a force, nor can it be replaced by a force, that is to say, the couple can not be balanced with a force, and the couple can only be balanced with the couple with the opposite direction

property 2: the moment of the couple to any point in its action plane is equal to the moment of the couple and has nothing to do with the position of the moment center

property 3: if two couples in the same plane have the same moment and the same direction, they are equivalent. It is called the equivalent condition of couple.

3. A is the fixed end, a force in X direction, a force in Y direction, and a couple.

4. Equal reversal

5. Because:
first, the vertical wall is smooth,
Second, CD is the vertical rope,
so the force of the two vertical walls on the homogeneous bar AB is equal and vertical to the wall,
so the two forces are a pair of couple.

6. If the couple moments of these two couples are equal, they are the same. The difference is that they are not the same, but they are all common. The couple should be as clear as the force in its three elements: the action surface (the plane of the two force action lines in the couple), the moment of the couple, and the turn of the couple (just use the right-hand spiral rule). In fact, with the right-hand spiral rule, the couple has only two elements (for theoretical mechanics), the size and direction of the moment.

7. We should add "acting on the same object" and "not on the same line" to form a pair of "couple". Because they do not act on the same object, there is no interaction between the two forces. If they act on the same object and are on the same straight line, the two forces are superposed instead of forming a couple.

8. Couple is composed of two opposite but parallel forces acting on the same rigid body

9. Of course. A force can be decomposed into a force and a couple, and vice versa; Furthermore, a force can be equivalent to two forces, so a force and a couple can also be equivalent to two forces. See theoretical mechanics

10.

Couple is a physical term. A pair of parallel forces with equal size, opposite direction but not collinear acting on the same rigid body is called couple. Under the action of concentrated couple, the shear diagram does not change

In general, the force system composed of two parallel forces acting on the same rigid body, which are equal in size and opposite in direction but not collinear, is called a couple. The couple is a vector. The couple is a force system with only resultant torque (the sum of all torques) and no resultant force. Therefore, it is also called pure torque. Acting on the object, the couple can make the object not present any translational motion, only pure rotational motion. The simplest couple is made up of two forces of equal size and opposite direction. The SI unit of the couple is Newton * meter. Couple refers to two special force systems with equal size and opposite direction

reference materials Network -- couple