Velocity (speed) and acceleration can have both negative and positive values, but not at the same time.
Velocity refers to the rate at which an object's position changes. It is a vector quantity that has both magnitude (speed) and direction. The sign of velocity indicates the direction of motion. Positive velocity indicates motion in one direction, while negative velocity indicates motion in the opposite direction.
Acceleration, on the other hand, refers to the rate at which an object's velocity changes. Like velocity, acceleration is also a vector quantity with both magnitude and direction. The sign of acceleration indicates whether the object is accelerating in the same direction as its velocity (positive acceleration) or in the opposite direction (negative acceleration or deceleration).
Therefore, while velocity and acceleration can have both positive and negative values, they cannot have opposite signs at the same time. If velocity is positive, indicating motion in one direction, then acceleration can also be positive (accelerating in the same direction) or negative (decelerating in the opposite direction). Conversely, if velocity is negative, indicating motion in the opposite direction, then acceleration can also be positive (accelerating in the opposite direction) or negative (decelerating in the same direction).