Well, speed is different from velocity but only because velocity is any speed which travels at a specific direction, but speed is how fast you move in any direction, but the equation for speed is the distance travelled in metres divided by the time you took to travel that distance. but here is a more complicated equation for velocity: Velocity is the square root of the kinetic energy times the mass and divide it by 2. It's a more complicated one but if I were you I would apply the speed equation to get your average speed.
