Pulleys - Science experiments

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Pulley
A pulley is a wheel on an axle or shaft that is designed to support movement and change of direction of a taut cable or belt, or transfer of power between the shaft and cable or belt.
  • Overcome friction
a wheel with a grooved rim around which a cord passes. It acts to change the direction of a force applied to the cord and is chiefly used (typically in combination) to raise heavy weights.

Types of pulley
Fixed :
Pulley is fixed and load is moved using pulley.
A fixed pulley changes the direction of the force on a rope or belt that moves along its circumference
A fixed pulley has an axle mounted in bearings attached to a supporting structure



















Movable :
Pulley is attached to load.
A single movable pulley is supported by two parts of the same rope and has a mechanical advantage of two
A movable pulley has an axle in a movable block..


Compound (Block and Tackle)
A block and tackle can have several pulleys mounted on the fixed and moving axles, further increasing the mechanical advantage.

A combination of fixed and movable pulleys forms a block and tackle.





Advantages of pulley:
  • Reduce and overcome friction
  • Reduce force needed to lift load
  • Redistribute direction of force
Titbits :
  • Movable pulley : by adding counter weight to other side helps add pull force needed to counter force
  • No of ropes to movable pulley determines mechanical advantage
  • Block and tackle is multiple movables pulleys combined to minimize hardware








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