This demonstration uses two broom handles and a long rope to model a block and tackle pulley system. It shows how increasing the number of rope loops reduces the effort needed to pull two volunteers together, demonstrating mechanical advantage.

1. Choose three student volunteers: two to hold broom handles and one to pull the rope.
2. Give gloves to the two broom-handle holders and have them stand 5–6 feet apart, holding the broom handles parallel to the ground at waist height.
3. Tie one end of the rope securely to the center of one broom handle.
4. Wrap the rope around the middle of the other broom handle, then hand the free end to the rope puller.
5. Position the rope puller slightly behind and to the side of one broom-handle holder so the rope is pulled parallel to the ground.
6. Have the rope puller pull steadily while the two holders resist being drawn together.
7. Repeat the activity, wrapping the rope additional times around the broom handles to increase the number of loops. Observe how the effort required changes.

Pulley fun! a fun, at-home science experiment - Science Beyond:

📄 Simple Block and Tackle Pulley Demonstration - Flinn Scientific: https://www.flinnsci.com/api/library/Download/77cdc16656df4bf6b673631749784ee4

• Try different numbers of rope wraps and compare the effort needed each time.
• Use a spring scale on the rope to measure input force at different stages.
• Replace broom handles with dowels or PVC pipe to test different materials.

• Wear cloth gloves to prevent rope abrasions.
• Keep the area clear to avoid tripping hazards.
• Pull the rope evenly - do not jerk or yank, as this could cause injury.
• Avoid rubbing the rope against participants’ hands.

• What is the mechanical advantage of a block and tackle system? (It equals the number of supporting rope segments lifting the load.)
• Why does adding more loops make lifting easier? (The effort force is divided across more rope segments, reducing the input force required.)
• What is sacrificed when mechanical advantage increases? (The rope must be pulled a longer distance to move the load the same amount.)
• How does this demonstration relate to real-world pulley systems, such as cranes and elevators? (It models how pulleys reduce effort in lifting heavy objects by trading distance for force.)