Final answer:
In Physics, acceleration is a vector quantity that affects an object's velocity by changing its speed or direction. The object speeds up if acceleration is in the same direction as the velocity and slows down if it is in the opposite direction. Acceleration plays a critical role in determining the motion of an object and is integrated into the kinematic equations describing motion.
Step-by-step explanation:
The question addresses a concept from Physics, specifically the topic of acceleration and its role in the motion of an object. Acceleration is a vector quantity, which means it has both magnitude and direction. Contrary to what may be intuitive, acceleration does not only refer to increases in speed; it also refers to changes in the speed's direction, commonly experienced as speeding up or slowing down. The direction of an object's acceleration relative to its velocity determines whether the object will increase or decrease in speed.
Two important forms of acceleration are tangential and centripetal acceleration. Tangential acceleration is in the direction of the change in velocity, while centripetal acceleration causes an object to change direction, such as when a car turns a corner at a constant speed and is considered to be accelerating due to the change in direction.
When adding acceleration to the velocity of an object in motion, the motion is affected as follows: If the acceleration vector has the same sign as the velocity, the speed increases, and if they have opposite signs, the speed decreases. The kinematic equations help us understand motion in one-dimension by incorporating acceleration as the second derivative of the position function. Projectiles, such as a thrown ball or a launched missile, follow a trajectory affected by acceleration due to gravity, where such acceleration is constant.