Acceleration as a vector quantity is generally defined as the rate of change of velocity. An object such as a vehicle or a thrown stone is said to be accelerating if it is changing it velocity(Hamann, Morse & Sefusatti 2005). Acceleration therefore has to do with changing how fast an object is moving and it therefore does not necessarily mean how fast an object is moving.

The other definition, which is not so much different from the first one, describes acceleration as the rate at which the velocity of any body or object changes with respect to time. This definition clearly brings out time as a component of acceleration(Kakalios 2005)**. **Just as velocity is a vector quantity, acceleration is also a vector quantity that posses both magnitude and direction. Since acceleration can be derived by dividing velocity with time, the SI unit of acceleration is therefore the meter per second per second. This is because the velocity in meters per second changes by the value of acceleration every second (Kaplan 1963). Other books would still define acceleration as the second derivative of position with respect to time, which is otherwise the first derivative of velocity with respect to time. The SI unit for acceleration is symbolized as m / s^{2 }(Bryant 2009).

The one and major advantage of acceleration is that it has contributed to the field of science immensely and given scientists a way in which they are able to differentiate what velocity is and acceleration (Hamann, Morse & Sefusatti 2005). The other advantage is that acceleration is designed to be precise in its measurements; this makes them give quite accurate presentations based on such precision. The disadvantages on the other hand are quite a number: - the acceleration equation and formula is quite complex, this is because it does not permit for the use of a constant one to make it look compact. The vector quantity of acceleration also exhibits difficulty in its physical interpretation; this is because they do not subsume the dimensional analysis outright (Kakalios 2005).

In literature, the student’s understanding of acceleration is well documented. The bit that students find hard to apply is the point when an object is experiencing a circular motion. This is because objects moving in a straight line are easy to deal with as acceleration simply means the scalar component of velocity (Shukla & Srivastava 2006). The definition and description of acceleration demands for a cross-dimensional approaches because the disregard of this would lead the concerned parties into a misunderstanding of what exactly velocity, acceleration and speed is (Kaplan 1963).

The description of the bodies as they apply to acceleration does not apply to human beings in most of the instances. In cases that the bodies are, human beings then they are not observing their acceleration (Kakalios 2005). Acceleration is therefore not a possibility in instances when motion is given the approach of only one dimension. This fact would also lead to confusion when it comes to differentiating between speed and velocity and by far between scalar and vector quantities (Hamann, Morse & Sefusatti 2005). In most discussions, students have been adamant on insisting that acceleration is at zero in the highest point for a stone thrown up in the air. This is a situation, which does not and will never apply to any object, which is at rest; this confusion from the inability of such scholars to separate between speed and velocity (Kakalios 2005).

Acceleration as the change in velocity is a concept that is vital in the field of science and by extent in physics (Shukla & Srivastava 2006). The concept requires an understanding by scholars. Its merits are immense while the demerits are also a number and require a consideration for the usefulness of the concept realization.