Physics Chapter on Pulleys

Study Notes

A pulley is a grooved wheel that rotates around a fixed axis, typically driven by a rope.
Pulleys can function as fixed or movable systems, aiding in the direction and magnitude of applied force.

Designed to change the direction of a force without altering its magnitude.
Typically used to apply traction or weights at various angles.
Consists of a fixed pulley block and a rope with one end attached to a weight and the other to the applied effort.

Provide mechanical advantage, allowing heavier weights to be lifted more easily.
Feature an upper pulley fixed to an overhead support, with the rope wrapped around the movable pulley where the weight is attached.
The effort is applied at the free end of the rope.

In anatomy, bones, cartilage, or ligaments replace mechanical pulleys, with muscles represented by tendons.
Tendons are lubricated to allow smooth movement over these anatomical pulleys.
Anatomical pulleys enhance muscle function by aiding in the movement and placement of tendons over external supports.

Class I:
- Involves tendons passing over external supports (e.g., patella acts as a pulley for quadriceps, improving insertion angle).
Class II:
- Alters muscle action at the joint through:
  - Bone: Lateral malleolus serves as a pulley for the peroneus longus muscle, enabling proper ankle movement.
  - Cartilage: Trochlea of the eye allows the superior oblique muscle to rotate the eye, enhancing functionality.
  - Ligament: Retinacular structures stabilize flexor tendons in the hand, promoting efficient finger flexion through the carpal ligament and digital flexor pulley systems.
Class III:
- The joint itself serves as the pulley, facilitating movement.