M.1.1 Vector Addition

This apparatus consists of a platform that rolls along the lecture table, and some toy bulldozers or carts to roll on it. You can push the rolling platform with your hand or let a bulldozer push it. The angle between the motions is completely adjustable. The demonstration can be shown in several versions:

A. As a qualitative illustration, let the bulldozers move and sketch the resulting vectors on the blackboard.

B. To illustrate the path of a boat crossing a river, set the bulldozer rolling on the platform at slight back angle and mark a direction perpendicular to the platform motion on the lecture table with blocks. With the correct adjustments, the bulldozer moving on the platform will be seen to cross the shortest distance perpendicular to the "current".

C. The apparatus is set up on butcher paper, the initial positions of the bulldozers marked, and their final positions marked after the bulldozers have moved. Then the butcher paper can be taped up on the blackboard and the vectors sketched in.

D. In an elaborate demonstration, apparatus is set up as in the illustration above with a bulldozer pushing a blinky while a picture is taken of three blinky tracks as first one bulldozer moves, then the other, and then both. The picture is developed in ten seconds and projected on the screen so the students can see the three blinky tracks.