These equations describe motion while acceleration stays constant. List what you know and what you need. Choose the equation containing those quantities, then decide signs and units.

The model has a domain of validity. Explain its assumptions before using it in a changed context, then compare your prediction with evidence.

• For constant acceleration, list knowns and the requested unknown. Choose a relationship that excludes the quantity you lack.
• Do not substitute numbers before deciding their directional signs. These equations assume constant acceleration.