Pulley Lab
Name: ____________
Objective: Pulleys are in the world all around us. How does the number of strings in a pulley affect the amount of effort needed to lift an object?
Hypothesis: I think the greater number of strings will increase/decrease
(circle one) the amount of effort needed to lift an object because
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Materials: (per group)
1 broom handle (or long pole)
1 jug with a closed handle filled with water
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Length of rope
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Duct tape
Procedure:
1) Tape the broom handle between two desktops.
2) Tie the rope around through handle of the jug once, then loop over the broom handle and use the rope to lift the jug.
3) Untie.
4) Tie the rope around the broom, loop the rope through the jug handle and lift the jug by the free end of the rope.
5) Pull the loop through the jug handle again so that you have a double loop and lift the jug by the free end of the rope.
6) Pull the loop through the jug handle again so that you have a triple loop and lift the jug by the free end of the rope.
Pulley with double loop

Observations: (What I see/smell/touch/hear/taste)
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Conclusion: (What happened, Was my hypothesis right or wrong, so what?)
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Extension:
*If your school has spring scales, use spring scales to measure the force needed to lift the pulley at the different stages.
Adapted from: http://www.grc.nasa.gov/WWW/K-12/Summer_Training/KaeAvenueES/pulleys.html