First Law: net inertia. Subjects at rest tend to stay at rest until you settle in. Then they spring into action, usually of the death-defying (or at least social-convention-defying) sort. Conversely, subjects in motion will tend to stay in motion until such time as you enjoy their motion. Then they will stop.

Second Law: F=ma. The relationship between the force needed to cajole a small person into even the most pleasant task is Force=(minutes needed to perform task without small children)x(age, in years, you feel after the task is complete). Exempli gratia, force required to put on child’s shoes=(.25)x(57)=14. Units may vary. 14 minutes, 14 different techniques, 14 different pair before they finally agree to leave one on, 14 threats to leave without said child.

Third Law:  For every action there is an equal and opposite reaction. You get dressed, they glitter paint the cat. You prepare breakfast, they remove all the tape flags from your research books. You strike up a conversation with the clerk at the market, they strip down naked and run away laughing.

You don’t see how those are equal and opposite? You must possess logic and reason, then. Ah. You must not have children.