Experiment:Lifting weights using pulleys

Aim: To use pulleys to lift loads

Materials:  4 single pulleys, string, 1kg mass/a tin filled with sand, spring balance, clamp stand, meter rule

Method

1. Set up a fixed pulley as shown above
2. Place a 1kg (about 1 Newton) load on one end of the spring
3. Use a spring balance/force meter to find the effort required to lift the load
4. Set up a  single movable pulley
5. Determine the force required to lift the 1 kg load
6. Set up a block and tackle pulley using a single movable pulley and a fixed pulley as shown above
7. Determine the force required to lift the 1 kg load
8. Set up two fixed pulleys and two movable pulleys as shown above
9. Determine the effort required to lift the movable load

Observation and Results

• The Mechanical Advantage is below the expected figure due to friction and
• Where applicable the blocks below the fixed pulleys

• In simple terms the M.A and V.R of pulleys is equal to the number of movable pulleys multiplied by two

Conclusion

• Fixed pulleys change the direction of force without impacting on Mechanical Advantage or Velocity Ratio
• They make it convenient to move the load
• Movable pulleys have a Mechanical Advantage and Velocity Ratio of 2

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