OK, the “Compound Machines” event @ Science Olympiad is a closed event comprised of a written part and a more practical part, where the team needs to use a pre-built “scale” to determine an unknown mass with the help of a known mass. So I don’t have a real video or images of the event. All the pictures were done afterwards. The rules for the scale are in the official rulebook;-) I’ll just try to collect some “lessons learned” and some pictures for reference.
- Use the longest levers which still fit into the rules. With longer levers, the significance of the limited accuracy of the length measurements decreases.
- Find at least some parts with with “nice round” values. In our setup, the active length of the second class lever was 45 cm and the fixed side of the first class lever was 11.25 cm. That made the equation somewhat easier;-) Mu = 4 (a/d) Mk
- Try to find good bearings;-) Brass bushings with brass washers on both sides worked kind of OK.
- Make sure, you calibrate the apparatus with the hooks.
- Include the masses of the attachment hooks where you hang the masses in your calculations!! We missed that part during the preparation and so the results were somewhat off during the competition:-(
So overall, the Millennium team was not very successful in this event. But there is always next year;-) I hope, the kids learned something regardless. Just to keep track of the spreadsheet: Scale – Spreadsheet
Have fun;-)
Nice work! I have to build one of those for this year’s science Olympics and had a question for you. Since both levers are pivoting about an axis, the motion of the connected ends of both levers should be in circles about these axes. These circles should only touch in one place: at level. Therefore how would the levers above be able to move from level. I DO notice that the class one lever is hanging and therefore has some lateral motion built in. Maybe that’s the answer.
Yes, that’s the answer;-) As long as the lever does not move to far from level, the hanging setup compensates without introducing too much error;-) The pivotal point of the class one lever would move on a circle around the top/fix point of the hanging mechanism. You want to make that circle as large as possible so that the lateral movement does only force minimal vertical movement.