| Let's suppose Bill and Sam each push a ball. The same ball. Let's say that Bill wants to push the ball two feet to the right, and four feet up, while Sam intends to push the ball five feet to the right and one foot up. | |
| If one pushes, and then the other pushes, what is the ball's final destination? |  |
| Let's say that one of them pushes first, and then the other pushes (or pulls, for that matter), starting where the other finished. |  |
| Does it matter who pushes first? |  |
| Either way, the result is the same. |  |