We will use moment equilibrium around the x axis to calculate the x-component of the reaction torque at and the axial torque resultant at section , for these two shafts in torsion.

To calculate the x-component of the reaction torque and the axial torque resultant in torsion, we need to use the principles of moment equilibrium and torsional shear stress.

1. Moment Equilibrium:
Moment equilibrium means that the sum of all the torques acting on a system is equal to zero. In our case, we want to find the x-component of the reaction torque, which is the torque acting on one end of the shaft. To calculate this, we need to consider the torques due to applied loads or moments, as well as any torques due to internal forces.

2. Torsional Shear Stress:
Torsional shear stress refers to the stress acting on a shaft when it is subjected to a twisting force. The torque applied to the shaft induces shear stress throughout its cross-section, and the maximum shear stress occurs at the outermost surface of the shaft.

Now, let's go through the steps to calculate the x-component of the reaction torque and the axial torque resultant at the specified sections:

Step 1: Determine the applied loads and moments acting on the shaft. These could be given in the problem statement or need to be calculated based on the given information.

Step 2: Identify the torsional reactions at the supports. For example, if the shaft is simply supported or fixed at one end, there will be a reaction torque at that support.

Step 3: Calculate the moment arm of the reaction torque. The moment arm is the perpendicular distance between the axis of rotation and the line of action of the force causing the torque. It can be calculated using the geometry of the system.

Step 4: Use moment equilibrium around the x-axis to set up an equation. Consider all the torques acting on the shaft, including the applied loads, moments, and the reaction torque from the support.

Step 5: Solve the equation for the x-component of the reaction torque.

Step 6: To calculate the axial torque resultant at a specific section of the shaft, you need to consider the distribution of torques along the shaft. This will depend on the applied loads, moments, and any internal torques due to previous sections of the shaft. Use the principles of torsional shear stress to calculate the torque at the desired section.

It's important to note that the above steps provide a general methodology for calculating the x-component of the reaction torque and the axial torque resultant in torsion. The specific calculations will depend on the given parameters and the geometry of the problem.