Algodoo

Each of the 4 wagons of the train has to contain a ball, then the train strarts to travel.

To control this, logical tools are used: in each wagon is an orange lever, that pushes the upward-positioned (true, green) lever of a logical state into its downward-position ( false, red ) if a ball pushes this orange lever.

This changes the color of 4 squares, which are on the logic-processing-line, of which the first row simply negates (NOT) the state. In the second row two pairs of results of the first row are combined with AND, the left of them only produces true ( green ) , if both wagons on the left contain a ball, the right of them only produces true, if both wagons on the right contain a ball.

In the next row again an AND is used to process only true, if all wagons have a ball inside. This in turn is inverted, and serves as input for the last row for the "Soldimaker". The Solidmaker makes the block S1 solid, if he receives "true" as input. On the contrary, it makes S1 transluctent ( noninteracting ), if it receives "false".

So, if each waggon contains a ball, the block S1, which blocks the steering-wheel of the locomotive, becomes inactive, and the wheel can strart to turn and pull the train to the right.

To shoot balls, start the simulation and klick on the white arc. The balls start near the mouseposition and have momentum in the direction that the purple-colored circle indicates. Try to shoot as few balls as possible to start the train.