Yes, you choose A as the point to take moments about precisely because you don't want to be bothered with the reaction forces at A.mike41 said:
Tension is a pulling force that is applied to an object. In the context of a cable supporting a beam, tension is the force that is exerted on the cable as a result of the weight of the beam. If the tension in the cable is too high, it can cause the cable to snap, while if it is too low, the beam may not have enough support.
The tension in a cable supporting a beam can be calculated using the equation T = W / sinθ, where T is the tension in the cable, W is the weight of the beam, and θ is the angle between the cable and the horizontal plane. This equation assumes that the beam is in equilibrium and the cable is perfectly horizontal.
The tension in a cable supporting a beam can be affected by several factors, including the weight and dimensions of the beam, the angle of the cable, and the properties of the cable itself (such as its material and diameter). Other external factors, such as wind or vibrations, can also impact the tension in the cable.
To ensure that the tension in a cable supporting a beam is within a safe range, it is important to carefully calculate the tension using the appropriate equation and consider all relevant factors. It is also crucial to use high-quality materials for the cable and regularly inspect and maintain the cable to prevent any potential failures.
Calculating the tension in a cable supporting a beam is important in various real-life applications, such as construction projects, suspension bridges, and cable-stayed bridges. It is also essential in the design of cranes, elevators, and other structures that rely on cables for support.