The rate of change of an object's velocity.[1]. For an object to undergo an acceleration, a force needs to be exerted on the object. An example is a falling object on Earth, which is subject to a gravitational force. The resulting acceleration g is independent of the mass of the object, and is approximately 9.8 meter per second per second near the Earth's surface[2].
Calculation of acceleration is done with the formula 
, where F=force and is measured in Newtons, M=mass and is measured in kilograms, and A=acceleration. Using the formula we can find that 
.
If an object's acceleration and velocity have the same sign, the object is gaining speed. If acceleration and velocity have different signs, the object is losing speed.