1. Speed is the time rate at which an object is moving along a path, while velocity is the rate and direction of an object's movement.
2. The formula for speed is speed = distance ÷ time. Distance is in meters (m) and time is in seconds (s) so the units will be meters per second (m/s)
3. A horizontal line on a speed-time graph represents a constant speed. A sloping line on a speed-time graph represents an acceleration. The sloping line shows that the speed of the object is changing. The object is either speeding up or slowing down.