Band-rollers are a great way of introducing or extending the subject of forces. They are the simplest and cheapest way of producing something that moves. In this section there are pages to show how to make a band-roller (either at home or at school, how to use them for testing different surfaces for friction and how to sequence an explanation of how the band-roller works.
Download the worksheet
Equipment
Wire, cut into 9 cm lengths
12 cm 3mm dowel, cut into 2 and 10 cm lengths
Card Discs
Metal washer
Cotton Reel
Elastic Bands: use the smallest size possible (28mm x 1.5mm is ideal). Be aware of allergies A nice variant is to try loom bands (which are non-allergic) – the material is not quite as stretchy, so, in theory, loom-band powered band-rollers will not perform as well as elastic band ones.
Costs (via Ivydale Technology Service: other suppliers may differ)
Wire: £8 for 100 metres. Cost of 9 cm = 0.8p
3mm Dowel Cost of 60 cms is 20 p. Cost of 12 cm 4p
Card discs £9/100. Cost of 2 18p
Metal washers £1/100. Cost of 1 1p
Cotton Reel £6/50 Cost of 1 12p
Elastic bands (via Amazon) £4/1000. Cost of 2 0.8p
Total cost/pack: 36.6p The main costs are the card discs and the cotton-reel – removing these items brings the cost to 6.6p/pack. This is possible, using scrap materials click here
As the band returns to the original shape, there is a turning force on the winder.
The elastic band tries to go back to its original shape because it is elastic.
The force of friction between the roller and the floor will slow and eventually stop the roller.
The roller will keep moving while the elastic band unwinds.
The washer reduces force between the winder and the side of the roller.
The winder cannot turn because the floor is in the way.
This means that the roller turns so that the elastic band can unwind.
When the roller turns, it moves across the floor.
When there is no longer a force provided by the elastic band the roller will stop.
When you turn the winder the elastic band is twisted out of shape
Download printable version