Speed - the rate of change of position. Speed = Distance / Time. Common units utilized for speed are meters per second (m/s) or miles per hour (mi/h).
Velocity - the rate of change of position. Velocity = Displacement / Time. Common units utilized for velocity are meters per second (m/s) or miles per hour (mi/h).
The main difference between speed and velocity is that speed is a scalar quantity (does not depend on direction) whereas velocity is a vector quantity (which does depend on direction).
Acceleration - Change of velocity over time. Force = Mass x Acceleration. Acceleration = Force / Mass. Common used units of acceleration are meters per second squared (m/s^2).
