Many years ago I and my class made a Push-Pull Meters with dowel rod and a cotton reels and had great fun with them, measuring all sorts of pushes and pulls.OK we could have used conventional force meters, the school had enough of them for class use, however making one yourself and then using it seems to make a big difference in understanding.
A recent question made me look for my plans – no chance. Search the internet – no luck. My team were of no help so I therefore decided to do the obvious thing, make one myself.
These are the drawings of my endeavours. The equipment list is cotton reel (wooden would be nice but if it’s plastic ok), a length of dowel rod with a diameter which will allow it to pass through the central hole of the cotton reel, an elastic band (probably 4 cm long but have a set of them for experimentation), a paperclip which is opened up to make a hook, some drawing pins or sellotape …….and I think thats it.
Once constructed the next task it to calibrate it. If you have access to a set of weights, great. you can create a little bag which will hold them, hang it on the hook and away you go. A 1kg mass will apply a 1 Newton force on the elastic band. This is where the choice of the elastic band is important – a thin band is obviously much more sensitive than a thick band. On the other hand, why not make up your own scale of push a pulls – a five marble/ 3 marble/1 marble push or pull. Below are the images that I created for my answer to the 10 yr olds question.