Linear velocity describes the speed and direction of a body or body segment moving through space in a straight line, typically measured in meters per second (m/s) or feet per second (ft/s).
In biomechanical analysis, linear velocity helps quantify:
- Sprint Speed: How fast an athlete is running
- Projectile Motion: The velocity of a ball being thrown or kicked
- Center of Mass Movement: How quickly the body's center moves through space
- Limb Endpoint Velocity: The speed of hands, feet, or other distal segments
Linear velocity has three key components:
1. Magnitude: The speed of movement 2. Direction: The path of motion through space 3. Rate of Change: How velocity changes over time (acceleration)
Video analysis systems can track markers or body segments frame-by-frame to calculate instantaneous linear velocity at any point during a movement. This data is crucial for:
- Performance optimization (maximizing speed in sprinting or striking movements)
- Technique evaluation (ensuring proper sequencing and timing)
- Injury biomechanics (understanding impact velocities)
The relationship between angular velocity and linear velocity is particularly important at joints, where rotational motion of segments creates linear motion of distal endpoints (like the hand in a throwing motion).