If Junior just remembered that the Science Fair project is due tomorrow, and he hasn’t even started, there’s no need to panic. The little project shown here can easily be whipped up in an evening, and the teacher will be none the wiser about your haste. He or she will assume that the little scientist has been working on it for weeks.
While Mom and Dad race to the dollar store before it closes to buy the poster board and markers, Junior can start building this instrument for measuring wind resistance for objects of various sizes. Unless someone sticks their fingers into the moving fan blades, this experiment should be completely safe. It appeared 80 years ago this month in the May 1937 issue of Popular Science.
Of course, the teacher expects the students to come up with things like a hypothesis, which should be pretty easy. All Junior needs to do is come up with a sentence such as “a ______ shaped object has more wind resistance than a ______ shaped object.” The blanks can be filled in with whatever objects are easier to construct, for example, a cube and a sphere.
The instrument shown here is pretty self-explanatory. The object being tested is mounted on top of a rigid wire, with a counterweight at the bottom. To make it look fancy, you can make the pointer and scale. Then, you balance the wire and blow a fan at it. The object that deflects the furthest has the greater wind resistance.
As can be seen here, the fan has an “egg box partition” in front of it to straighten out the air currents. Apparently, in 1937, most households had egg boxes lying around with cardboard partitions. A modern egg carton probably won’t work, but Junior can retrieve some cardboard from the recycling bin and simply make a grate consisting of square openings.
When you get home with the poster board, Junior can copy down some interesting facts from the Wikipedia article about drag, and the result will probably be a blue ribbon.