Build a pulley
Build a simple pulley system using a spool, rope, and hook to lift small weights, exploring mechanical advantage and force safely.
Step-by-step guide to build a simple pulley system
Step 1
Gather all the Materials Needed and bring them to a clear workspace.
Step 2
Ask an adult to hang the S-hook on a sturdy overhead support like a curtain rod or broom handle.
Step 3
Tie one end of the long rope securely to the top of the S-hook with a tight knot.
Step 4
Put the long rope into the groove around the spool so the rope runs under the spool.
Step 5
Cut a short piece of rope about 10 centimeters long using the scissors.
Step 6
Thread the short rope through the center hole of the spool.
Step 7
Tie the ends of the short rope together to make a strong loop for hanging weights.
Step 8
Slide small washers or toy weights onto the short rope loop so they hang from the spool.
Step 9
Tape the weights to the loop if any pieces wobble or fall off.
Step 10
Hold the free end of the long rope and pull slowly to lift the spool and its weights.
Step 11
Add one more small weight to the loop to make the load a bit heavier.
Step 12
Pull the free end of the long rope again and see if you can lift the heavier load.
Step 13
Take the same weights off the loop and hold them in your hand to feel how heavy they are without the pulley.
Step 14
Pull the free rope end one more time and notice how the pulley changed the effort compared to lifting by hand.
Step 15
Share your finished pulley and what you discovered about force and mechanical advantage on DIY.org.
Final steps
You're almost there! Complete all the steps, bring your creation to life, post it, and conquer the challenge!
Help!?
What can we use if we can't find an S-hook, a spool, or small washers?
Use a bent coat-hanger or carabiner hung over a door frame instead of an S-hook, an empty thread spool or a bottle cap with a groove instead of the wooden spool, and coins or metal nuts in place of washers while keeping the long rope and short rope as described.
Why won't the spool lift when we pull the long rope, and how do we fix it?
Make sure the long rope is tied tightly to the S-hook, that the long rope runs under the spool inside the groove as step 4 says, that the short rope loop is securely knotted and weights are taped if they wobble, and pull the free end slowly rather than jerking it.
How can we adapt this pulley activity for younger or older kids?
For younger children, have an adult hang the S-hook, cut the short rope, slide on larger lightweight toy weights and tape them for safety, and let the child pull slowly, while older kids can add heavier washers, measure effort, or try adding another pulley to explore mechanical advantage.
How can we extend or personalize the pulley once it's working?
Turn it into a block-and-tackle by adding a second spool and S-hook to compare the effort when you pull the free end, decorate the spool, and share your observations about force and mechanical advantage on DIY.org.
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Facts about simple machines and pulleys
⚙️ A single fixed pulley only changes the direction of the force — it doesn’t multiply how strong you are (mechanical advantage = 1).
⛵ Sailors relied on block and tackle (multiple pulleys) to lift heavy sails and cargo with much less effort.
🪜 A single movable pulley halves the force needed to lift an object, giving a mechanical advantage of about 2.
🧰 Pulleys are one of the six classical simple machines people have used for thousands of years.
🧠 To estimate mechanical advantage in many pulley setups, count how many rope segments support the load — more segments usually mean more advantage.
How do I build a simple pulley with a spool, rope, and hook?
What materials do I need to build a pulley system for kids?
What ages is building a simple pulley suitable for?
What are the benefits and safety tips for making a kids' pulley, and are there variations?
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