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PHY.4:3 - Forces
| Force | Tension |
|---|
| Unknown mechanism and usable physical grounds | Partial knowledge can constrain the law, while a premise about an omitted influence can invalidate the constraint. |
| Changed description and changed experiment | Coordinates can change without changing the situation; changing the apparatus alone can alter its relation to the surroundings. |
| Strong restriction and remaining freedom | A direction, sign or balance can be established while the magnitude law remains unknown. |
| Idealized comparison and intended use | A conditional law family can guide work before all its physical premises have been resolved for an application. |