A single pulley with a radius of 2 inches has what kind of mechanical advantage (MA)?

In the case of a single pulley, the mechanical advantage is determined by the relationship between the load force and the effort force. A single, fixed pulley provides a mechanical advantage of 1 to 1, which means that the force you apply to lift the load is equal to the weight of the load being lifted.

The radius of the pulley, while it relates to the distance over which the force is applied and can influence the torque, does not change the mechanical advantage of a single, fixed pulley system. Therefore, regardless of a 2-inch radius, the mechanical advantage remains 1 to 1.

This is because no additional support for lifting the load is given beyond the pulley itself; it just allows for changes in direction of the force applied. Hence, when using a single pulley, for every unit of weight, an equal unit of effort is needed to lift it, resulting in a straightforward mechanical advantage of 1 to 1.