Velocity
![](/Images/godic/202501/20/US_Navy_040501-N-1336S-037_The_U.S._Navy_sponsored_Chevy_Monte_Carlo_NASCAR_leads_a_pack_into_turn_four_at_California_Speedway2626.jpg")
![Kinematic quantities of a classical particle: mass m, position r, velocity v, acceleration a.](/Images/godic/202501/20/Kinematics.svg2626.png")
![Example of a velocity vs. time graph, and the relationship between velocity v on the y-axis, acceleration a (the three green tangent lines represent the values for acceleration at different points along the curve) and displacement s (the yellow area under the curve.)](/Images/godic/202501/20/Velocity_vs_time_graph.svg2626.png")
The velocity of an object is the rate of change of its position with respect to a frame of reference, and is a function of time. Velocity is equivalent to a specification of its speed and direction of motion (e.g. 60 km/h to the north). Velocity is an important concept in kinematics, the branch of classical mechanics that describes the motion of bodies.