A pulley is a simple machine that changes the direction of an applied force, makes it easier to pull a rope or weight. Pulleys have been helping people get their work done more easily since around 250 B.C. Teach children about pulley mechanics by having them create a single fixed pulley. It requires only a few simple and inexpensive materials and little time to accomplish, while allowing kids to experience how a pulley works hands-on.
- Skill level:
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Things you need
- Wire hanger
- Wire cutter
- Empty thread spool
Cut the bottom of the wire hanger in the centre with wire cutters.
Push the cut ends of the hanger through the centre of the thread spool so that they each enter through one side and protrude out through the other side. Bend the ends of the wire down to hold it onto the thread spool. Leave enough space when making your bends so that the spool can spin freely.
Hang the hanger with the spool from something sturdy like a cup hook or closet rod. Make sure that the hanger can hang freely without any obstructions.
Tie the end of a piece of string onto a book and pass the other end of the string once around the thread spool so that the free end hangs from the opposite side of the spool as the book.
Pull the loose end of the string to lift the book.
Tips and warnings
- A single fixed pulley has a mechanical advantage of one. A value of one means that there is no advantage or disadvantage, but by combining multiple pulleys you can create a mechanical advantage. In other words, you can reduce the amount of force needed to lift a load. The more pulleys in the system, the less force you need to lift the load.
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