求翻译：利用截面法将螺栓沿剪切面截开一分为二，取下半部分为研究对象，考虑其平衡知：上半部分对下半部分的作用力的合力为一与P大小相等、方向相反、作用线相互平行的力，该力也与剪切面平行，通常称为剪力，以Q记之。是什么意思？

Section method used to cut open the bolt along the shear plane into two, take the lower half of the object, consider the balance of knowledge: the lower half of the upper half of the force on the force for a and P are equal and opposite, parallel line of action force, the force is parallel with the

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Cuts open using the method of sections the bolt along the shear plane the one divides into two, takes down the half to divide into the object of study, considers its balanced knowledge: The upper half minute to a lower part minute action is with joint forces one with the P size equal, the direction

Bolt by using section along the shear plane Und split into two, remove the second half for the study, taking into account its balance known: force on the lower half of the upper section of Heli is a and p equal and opposite, parallel to the line of action force, the force is parallel to the shear pl

Section method used to cut open the bolt along the shear plane into two, take the lower half of the object, consider the balance of knowledge: the lower half of the upper half of the force on the force for a and P are equal and opposite, parallel line of action force, the force is parallel with the