Kinematics is the study of motion. The system uses vector quantities, so displacement is used instead of distance. Displacement is almost the same as distance, the only difference is that since direction matters, displacement can be negative, distance cannot. As speed is to distance the vector version of speed that measures how fast something is displaced is velocity. Velocity is computed by this formula: where s is displacement and t is the change in time. Acceleration is when the velocity of an object is changing, typically at . To apply acceleration to displacement, there are four different kinematic formulas. One is where s is the displacement, is the initial velocity, and a is the acceleration.