How to Build a Pulley
Round up the necessary supplies., Cut the wire hanger at the bottom, right in the middle., Thread the open ends of the wire through the spool., Close off the wire hanger so that the spool stays in place., Loop the string over the top of the pulley...
Step-by-Step Guide
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Step 1: Round up the necessary supplies.
Pulleys are simple machines, and excellent ways to teach kids about forces, gravity, and efficiency.
To make simply pulleys, you should round up the following supplies, though there are substitutes available if you're missing something.
They will be discussed later.
Wire coat hanger String, rope, or cord (at least 10 feet) Wooden spool, like those found for thread (with a hole through the center) A weight to test, like a half-filled milk jug, book, piece of pipe, etc. -
Step 2: Cut the wire hanger at the bottom
Open it up so that you can thread the spool through the coat hanger.
The spool, which will function as you pulley, in the center of the wire.
The top of the hanger can be held or hung from the ceiling to make your pulley free-standing.
If you don't have a coat hanger, you can use:
Long skewers, dowels, or rods that you hold on either side.
String threaded through the spool, then tied up above. , Gently pry the cut in the wire open and put the spool on the coat hanger.
The less you try and bend things, the easier it will be to get the spool on while keeping the wire in place.If you can't get a wooden spool, try out:
Pre-made pulley wheels, found at most hardware stores for $5 or less.
Pulley wheels found in toy sets, like K'Nex building blocks.
Old ribbon spool, like for ribbon used in gift wrapping.
Toilet paper or paper towel roll, in a pinch. , You may have to bend the wire right around the spool, kinking it slightly to keep the spool in place if it is too heavy for the wires.
A good way to do this is to push both sides of the hanger close together so it is about half as wide as it was originally, then turn the two ends up so nothing can slide past them., It isn't a complicated stringing.
You just want the string draped over the top of the pulley.
When you pull down on one end of the string, the other end will get shorter as it moves up.
If you plan on doing a lot of experiments with pulleys, you could tie a small metal hook to one end of the string, allowing you to hang and test different weights from it with ease., Hang the top of the clothes hanger up so that the spool and string hang and can spin with ease.
You could have a friend hold the top of the clothes hanger as well.
If you're using a rod or towel around the spool, you can place two chairs near each other and balance the dowel on the tops of the two backs., It also makes it easier to pick something up, because you get to pull the string down, using gravity to assist you.
Feel how heavy your weight (half-full milk container, textbook, etc.) is before trying it on the pulley for comparison.
If you and your school have force meters, use them to test and record the weight before using a pulley. , Even rough pulleys (the wheel doesn't turn well, the string catches, etc.) will make it easier to pull up the book.
Why? Because you're moving with gravity by pulling down, making the motion more efficient.
More complicated and fine tuned pulleys, called "block and tackle" can even make it possible for one person to lift a car by themselves, though they require many pulleys acting together.
Test the weight with a force meter to see just how much easier your pulley makes lifting things. , Do things happen if the string gets longer? What if you used a bigger or smaller pulley wheel? Pulleys teach a lot about forces, gravity, and machines
-- what can you learn? Focus on finding ways to make the pulley more efficient to test how each part works.
What would happen if you added two more pulleys to the system, threading the string through them? Would it get easier to lift or harder? Easier.
Does the weight raise up the same amount as you pull the string back? Yes
-- the length of the string stays the same, so the length on both sides of the pulley will always add up to the same number -
Step 3: right in the middle.
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Step 4: Thread the open ends of the wire through the spool.
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Step 5: Close off the wire hanger so that the spool stays in place.
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Step 6: Loop the string over the top of the pulley.
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Step 7: Hang the pulley system up
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Step 8: making sure it can spin freely.
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Step 9: Tie the weight to one end of the string
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Step 10: Pulley's make your work easier by distributing the weight and forces across the "different" sides of strings created by the pulley.
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Step 11: Pull down on one end of the rope to bring the weight up with ease.
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Step 12: Ask yourself some questions
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Step 13: adjusting the pulley to test your experiment.
Detailed Guide
Pulleys are simple machines, and excellent ways to teach kids about forces, gravity, and efficiency.
To make simply pulleys, you should round up the following supplies, though there are substitutes available if you're missing something.
They will be discussed later.
Wire coat hanger String, rope, or cord (at least 10 feet) Wooden spool, like those found for thread (with a hole through the center) A weight to test, like a half-filled milk jug, book, piece of pipe, etc.
Open it up so that you can thread the spool through the coat hanger.
The spool, which will function as you pulley, in the center of the wire.
The top of the hanger can be held or hung from the ceiling to make your pulley free-standing.
If you don't have a coat hanger, you can use:
Long skewers, dowels, or rods that you hold on either side.
String threaded through the spool, then tied up above. , Gently pry the cut in the wire open and put the spool on the coat hanger.
The less you try and bend things, the easier it will be to get the spool on while keeping the wire in place.If you can't get a wooden spool, try out:
Pre-made pulley wheels, found at most hardware stores for $5 or less.
Pulley wheels found in toy sets, like K'Nex building blocks.
Old ribbon spool, like for ribbon used in gift wrapping.
Toilet paper or paper towel roll, in a pinch. , You may have to bend the wire right around the spool, kinking it slightly to keep the spool in place if it is too heavy for the wires.
A good way to do this is to push both sides of the hanger close together so it is about half as wide as it was originally, then turn the two ends up so nothing can slide past them., It isn't a complicated stringing.
You just want the string draped over the top of the pulley.
When you pull down on one end of the string, the other end will get shorter as it moves up.
If you plan on doing a lot of experiments with pulleys, you could tie a small metal hook to one end of the string, allowing you to hang and test different weights from it with ease., Hang the top of the clothes hanger up so that the spool and string hang and can spin with ease.
You could have a friend hold the top of the clothes hanger as well.
If you're using a rod or towel around the spool, you can place two chairs near each other and balance the dowel on the tops of the two backs., It also makes it easier to pick something up, because you get to pull the string down, using gravity to assist you.
Feel how heavy your weight (half-full milk container, textbook, etc.) is before trying it on the pulley for comparison.
If you and your school have force meters, use them to test and record the weight before using a pulley. , Even rough pulleys (the wheel doesn't turn well, the string catches, etc.) will make it easier to pull up the book.
Why? Because you're moving with gravity by pulling down, making the motion more efficient.
More complicated and fine tuned pulleys, called "block and tackle" can even make it possible for one person to lift a car by themselves, though they require many pulleys acting together.
Test the weight with a force meter to see just how much easier your pulley makes lifting things. , Do things happen if the string gets longer? What if you used a bigger or smaller pulley wheel? Pulleys teach a lot about forces, gravity, and machines
-- what can you learn? Focus on finding ways to make the pulley more efficient to test how each part works.
What would happen if you added two more pulleys to the system, threading the string through them? Would it get easier to lift or harder? Easier.
Does the weight raise up the same amount as you pull the string back? Yes
-- the length of the string stays the same, so the length on both sides of the pulley will always add up to the same number
About the Author
David Fisher
Brings years of experience writing about practical skills and related subjects.
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