From DT Online
A Shaduf (aka Shadoof) is hand-operated simple machine for lifting water to irrigate land still used in India, Africa, Egypt, and some other countries. Typically it consists of a long pole or beam mounted like a tall seesaw. There is a water bucket suspended from one end and a counterweight is positioned towards the other.
In use, the water bucket suspension rope is pulled down to lower the bucket into the water and then lifted out with the aid of the counterweight when filled. In both actions, the top beam serves mainly as a Class 1 Lever: pulling against the counterweight as the bucket is lowered and, as it is raised, the counterweight provides the Effort to lift the weight of water (plus a little extra effort provided by the operator pulling the bucket upwards).
- Build a model Shaduf and use it to lift a 1kg mass.
- How does the Shaduf make it easier to lift the mass?
- Does it matter where you position the counterweight?
- Should the counterweight balance an empty bucket or a bucket filled with water - or half filled with water?
- How heavy would the counterweight be to lift a litre of water?
- How might the design limit the height to which pyramid stones could have been lifted in this way?
- How would you make a larger model using garden canes for example?
- Structures and Frames can also be modelled using the Construction Kits listed in the Truss Bridges and Looking at Bridges articles.
Safety Point! Take great care with hot glue guns and all hot-melt glues. The melted glue can stick to the skin and cause severe burns.
|Clamp-on Hobby Vice
|Medium card coloured
|Thick card coloured
|10mm Squared Paper
|Bamboo Flower Sticks
- Choose metal cutting hacksaw blades - the teeth are small which suits this scale of work and they are safer for young children
- School PVA glue is best for young children because it is non-toxic and washes off : PVA Wood Glue is strongest but must be used with care.
- Try to get natural Flower Sticks or wear gloves because the green stain comes off on hands!