Final answer:
A fixed pulley changes the direction of force but not its magnitude, providing a MA of 1. When combined, pulleys can multiply the force, with each additional cable increasing the MA proportionately.
Step-by-step explanation:
A fixed pulley only changes the direction of the force. An ordinary pulley has a Mechanical Advantage (MA) of 1; it does not change the magnitude of the force applied. When multiple pulleys are used in combination, they can multiply the force exerted on the system. Such systems have more than one cable pulling directly upward, equating to the MA of the pulley system, which in a friction-free scenario, would equal the total output force as an integral multiple of the tension in the cable (T).
In context, when a single fixed pulley is employed, such as in a traction system to suspend a leg or to lift a heavy load, it simply redirects the exerted force without altering its magnitude. This results in a pulley system that facilitates the operation with ease, yet does not amplify the force exerted by the user.