Final answer:
Perpendicular forces do not change velocity because they act in the opposite direction of the applied force. Equal and opposite forces cancel each other out, resulting in a net force of zero. While they may affect acceleration, they do not affect velocity.
Step-by-step explanation:
Perpendicular forces do not change velocity because they act in the direction opposite the direction of the applied force.
When two equal and opposite forces are exerted on an object, they cancel each other out and result in a net force of zero. The cancellation of forces occurs when the forces act in opposite directions and have equal magnitudes.
While these forces may cause changes in acceleration, they do not cause changes in velocity.