The rate of change in the velocity of an object in intervals of time call acceleration. It is a vector quantity.
The direction of the force applied to an object determines the orientation of its acceleration. The Second Law of Newton describes the magnitude acceleration of an object. The magnitude accelerations combination effect of two causes:
- The amount of the net resulting force is directly proportional to the net balance of all external forces acting on that item.
- Mass of an object, which varies according to the materials used – magnitude is inversely proportional to weight.
The unit of acceleration (rate of change in the velocity) in the SI system is a meter per Second Square.
For example, a vehicle accelerates in the direction of motion. The vehicle starts from a stop (zero velocity) and travels in a straight line at increasing speeds. When the vehicle turns, it experiences accelerations are a new direction, changing its velocity vector.
Linear accelerations are present in vehicles in their present direction of motion. The travelers onboard notice linear accelerations as a force pushing them back into their seats.
The radial acceleration calls the resultant acceleration when changing direction. The passengers feel the reaction is a centrifugal force.
If the speed of the vehicle drops, this is acceleration in the other direction that is mathematically negative, known as deceleration or retardation. The passengers feel the response to deceleration as an inertial force pushing them forward.
Retrorocket burning in spacecraft is frequently used to create such negative accelerations. Because they are both changes in velocity, acceleration, and deceleration. Passengers feel each of these accelerations until their relative (difference) velocity about the vehicle is neutralized.