I found this off youtube, I hope it helps.
Speed = distance/time
10m/2s = 5m/s
The speed is 5 m/s
When parallel rays exit a concave lens, the light rays are divergent.
The rays diverge or bend away from the axis it has been traveling upon entering the lens when it reaches the other side of the lens. These rays appear to have come from the same focal point before entering the concave lens. When these parallel rays are extended, it will be traced back to a single point of origin.
