Roundabout challenge
Round and round they go … up and down … never tiring. Can you make a fairground roundabout out of K’NEX? Will people sit on horses on your roundabout, or on something else?
Levels of difficulty:
Level 1 - Make a simple roundabout that spins
Level 2 - As level 1, with a spring motor
Level 3 - As level 2, with seats that hang down and lean outwards as the roundabout turns
Equipment: K’NEX set, plus spring motor for level 2.
Approach: What shape will your roundabout be? How can you make a frame for it to stand on as it turns? How big will it be? Where will the people sit? For level 2, how can you make the spring motor turn the roundabout? Where will the motor fasten on to the frame? For level 3, can you make a number of seats, that hang freely below the roundabout when it turns? What happens to the seats when the roundabout turns fast?
Handy Hints (please click to view):
A2 - 3 ways to connect K'NEX rods and connectors
A4 - Making corners with blue & purple connectors
W5 - Wheels and tyres
W6 - Making rods turn with wheels or connectors
M1 - Spring Motor
Teachers' Notes
A project to build a model of a familiar mechanical object, and use it to investigate centripetal force.
Possible solution: See photo.
Before starting: Look at a picture of a fairground roundabout.
Conclusion: Firstly, check that the seats hanging down from each model lean out as the roundabout turns fast (if not, suggest the children change the hinges where the seat is attached to the wheel), and discuss why this happens (centripetal force). Then ask the children to carry out an experiment, to measure how far out the seats swing in relation to the number of turns that the spring motor has been wound up. Finally, draw tables and graphs of the results.
Copyright © Andy Shercliff 1996 and K'NEX User Group 2004
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