I am looking for some sensors which will enable me to measure the linear velocity of an object passing through a "gate". Essentially we can think of this as an object being fired (I can have the object go through a gate), and I will need the velocity of the object at the beginning/end of the gate. The speed of my object will likely range between 2 and 25 meters/sec. A good accuracy will be important (I would plan for at least within 0.1)
I would plan to attach to an arduino, however would be happy to purchase a ready made package and minimize the chance of error with my "tinkering".
Thanks for any suggestions.