In a pulley system, what force must be applied to balance a 10 pound weight?

To balance a weight in a pulley system, the force applied must equal the weight being lifted in order to achieve equilibrium. In this case, a 10-pound weight requires exactly 10 pounds of force to balance it. This principle is grounded in Newton's first law of motion, which states that an object at rest will remain at rest unless acted upon by an unbalanced force.

Thus, by applying a force of 10 pounds in the opposite direction of the weight, both forces effectively cancel each other out, resulting in no net movement. This demonstrates the fundamental concepts of force and equilibrium in mechanics. Any other force applied, such as 5 pounds or 15 pounds, would not properly balance the weight, leading either to movement or instability in the system.