- Two funnels
- Two liter-sized containers to place under the funnels
- One liter of rice
- One stop watch
Dump one liter of rice all at once into the funnel and time how long it takes for the rice to go completely through the funnel. Then, take the same liter of rice, the same funnel and the same stop watch, but this time pour the rice slowly and evenly into the funnel.
Based on previous experiments, we predict that you will shave roughly 1/3 off the flow time through gradual, controlled pouring. Running both funnels at once allows for an interesting side-by-side comparison.
The equipment used in the Doug MacDonald Challenge is available online from VWR International or you may request a 2006-2008 catalog by calling 1-800-932-5000.
- Support Stand Scienceware (page 447), Catalog # 12000-070; $19.50 each
- Wire Support Ring (page 445), 105mm (4"), Catalog # 60120-281; $15.60 each
- Clamp Holder (one is a bit more expensive than the other) (page 435), 19mm (3/4"), Catalog # 21572-501; $14.08 each
- 19mm (3/4"), Catalog # 21572-556 and it is for $21.20 each
- Imhoff Cone (page 2137), Wheaton # W990800, Catalog # 80080-902 ; $107.54 for a case of 4. (You will need to increase the inside diameter of the bottom of the cone to about ½ inch to re-create the experiment. A small handsaw works wonders.)