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Four large tractor wheels have fallen out of a helicopter flying over your school, and luckily landed in the playground when no-one was there. We need to put them on a lorry, as they are urgently needed by a local farmer. Can you help, by building a crane that will lift the wheels onto the back of the lorry?
Levels of difficulty:
Level 1 - Build a simple model of a crane Level 2 - Build a crane with a hook on the end of the string that goes up and down when you turn a handle Level 3 - As level 2, and the crane can pick up 4 of the larger KNEX wheels and tyres without falling over
Equipment: KNEX set, plus 1m length of string.
Approach: Do you know what cranes are used for? What do they look like? - there are lots of different types. How could you build one out of KNEX? What shape will it be? For level 2, how can you add a handle, and a length of string that will make a hook go up and down when you turn the handle? For level 3, test your crane with 4 wheels on the hook. Does it work OK, or does it overbalance? If it does, how can you improve the design to prevent it overbalancing?
A practical project to design and build a model of a familiar working object. At level 3, a project which demonstrates the effects of balanced and unbalanced forces on a static object.
Possible solution: See photo.
Before starting: Look at pictures or real examples of different types of crane, and discuss how they work.
Conclusion: Test all the models in the class, to see whose model can lift the most wheels. Discuss the different ways in which the models achieve the objective, and why the design of the winning model is the best.