Question

The given figure shows an arrangement of moving and fixed pulleys. Copy the diagram and show the direction and magnitude of forces exerted by the four strings marked 1 to 4. What is the load that can be lifted by the effort E? Calculate the mechanical advantage of this system.

Answer 1

1. The lowest movable pulley directly carries the load and is supported upwards by two string segments: String 2 and String 4.

Total Load (L) = Force in String 2 + Force in String 4

= 2E + 2E

= 4E

2. Mechanical advantage is calculated as the ratio of the load lifted to the effort applied:

Mechanical Advantage (MA) = `"Load (L)"/"Effort (E)"`

= `(4E)/E`

= 4