Silly as our application for this experiment may sound, we use this system to keep pens handy near the shopping list on the fridge. It’s saved us from many pen-searches over the years!
We install these at various places around the house (by the telephone, fridge, front door, anywhere that you usually need a pen at the last minute), and have even seen them at the counters of local video-rental stores.
[am4show have='p8;p9;p14;p41;p88;p92;' guest_error='Guest error message' user_error='User error message' ]
Download Student Worksheet
Troubleshooting: It’s important to note that the weight needs to slide freely both up and down the length of the cord (which is why fishing line is a great choice – the surface of the line is very low friction). Another important tip: the weights you use must weigh more than the object at the end of the string plus the force of friction in the lines (and the pulley). Hollow, metal objects work great like nuts (for bolts).
You’ll need to practice to find just the right balance point: where the pen flies up to its resting position when you let go of the pen.
This is a great addition to any tree house or playground structure! Hang a loop of rope from a tree branch (don't forget to thread the pulleys onto the rope before you tie the knot! Connect one pulley to the basket handle made from a circle of short rope. Tie a length of rope to the basket handle, then up through one tree pulley, down through the basket pulley, and up through the second tree pulley. Thread a 6" length of PVC pipe onto the end and tie the rope back onto itself to form a handle.
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We install these at various places around the house (by the telephone, fridge, front door, anywhere that you usually need a pen at the last minute), and have even seen them at the counters of local video-rental stores.
[am4show have='p8;p9;p14;p41;p88;p92;' guest_error='Guest error message' user_error='User error message' ]
Download Student Worksheet
Troubleshooting: It’s important to note that the weight needs to slide freely both up and down the length of the cord (which is why fishing line is a great choice – the surface of the line is very low friction). Another important tip: the weights you use must weigh more than the object at the end of the string plus the force of friction in the lines (and the pulley). Hollow, metal objects work great like nuts (for bolts).
You’ll need to practice to find just the right balance point: where the pen flies up to its resting position when you let go of the pen.
This is a great addition to any tree house or playground structure! Hang a loop of rope from a tree branch (don't forget to thread the pulleys onto the rope before you tie the knot! Connect one pulley to the basket handle made from a circle of short rope. Tie a length of rope to the basket handle, then up through one tree pulley, down through the basket pulley, and up through the second tree pulley. Thread a 6" length of PVC pipe onto the end and tie the rope back onto itself to form a handle.
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Try hitting refresh and play the video again. I got it to play all the way through to 4:38.
The video has stopped at 1:12 min. thanks 🙂
The ones in the video are from the window covering from a chicken coup I found at a farm supply store. I think the hardware stores are the easiest, but I did also include instructions for how to make a lightweight one from household items.
I think Home Depot carries the ones you want – they don’t have to be heavy duty.
We got ours from the hardware store.
Can you please suggest a supplier for the pulleys?
Why isn’t it working for me? My total weight is decidedly more than the pen I have attached to the end. I am using commercial pulleys just like the ones in the video and fishing line. Is it because I’m using too many weights? I’ve got two small bolts and four washers. Is that too many? Do I need to find something heavier that I can use less of?