A Force is a push or a pull A Force is a push or a pull. A force gives energy to an object causing an object to start moving, stop moving, or change its motion. Forces occur in pairs and can be either balanced or unbalanced. “Balanced” forces DO NOT cause a change in motion. They are equal in size and opposite in direction. “Unbalanced” forces always cause a change in motion. (Equal forces, opposite direction. Net Force = zero. Motion stays same.

Forces in same direction + = combine by addition. Forces balanced. Equal and moving in opposite directions. Net force equal zero Motion remains the same. = Forces unbalanced. Add together, one positive, one negative. Larger force minus smaller force = net force. Motion is changing. Forces in same direction + = combine by addition.

Forces in opposite direction combine by subtraction. = Arrows moving to the right or up are positive while arrows moving to the left or down are negative.