A 1 cm hailstone has a theoretical warp speed of about 20 mph (9 meters/second). Bigger hailstones have a much greater warp speed. And a ten-gram hailstone falling from 10 km (this range is most likely sufficient) has a terminal velocity of about 15 meters per second. 
Hail Damage Repair
Hail damaged metal roofing, tile roofing, wood shingle or shake roofings: might be evident as the loss of metal coatings by hail scouring, dents in metal roof, damages in wood shingles or shakes, or damaged clay or concrete tile roof coverings.
If your roofing system was just recently harmed by a storm you might need to repair or replace your roofing before more damage occurs. In sum, ask the roofing inspector for specific information that support his or her conclusions about the condition of the roofing and about exactly what caused its damage or wear. In other cases, if only a few bundles of shingles were faulty, say from incorrect manufacture or storage, asphalt shingle blistering might appear in shingles in a particular pattern on a roofing following the application pattern of the shingles themselves as they were nailed to the roofing.
-- If the Source damage is not addressed in the timely manner, 3 things could happen: 1) the lifespan of your roofing system is drastically minimized hence making you too soon change the roofing. If I were an insurance coverage adjuster, in my OPINION, I would think about offering a pro-rated allowance for hail damage on a roofing by figuring out - the roof's remaining life before the hail damage happened (infer this by analyzing non-scoured shingles or non-scoured roofing system slopes as often hail is directional and so damage is not at all uniform) - the estimated decrease in staying roofing system life because of the hail damage - if some slopes were not hail damaged at all I 'd exclude them from the adjustment I don't think the answer to amount of damage is based on number of stone hits per square, but rather, we should look carefully at the shingles to see the total level of granule loss over the whole roofing, and the DEPTH of granule loss on shingles, and in specific, if there is bald shingle substrate exposed on shingles, those specific shingles have a brief staying life (to be more particular we require to think about slope, age, environment and other aspects). As an insurance coverage adjuster (which I am not, though I do recommend insurance companies and adjusters as a neutral expert), in deciding to provide an allowance and to motivate roofing system replacement within that period, I would be thinking about also a wish to reducce or even avoid the danger of a future residential or commercial property loss due to a roof leak on a roof that should have been replaced sooner. If your roofing was just recently harmed by a storm you might need to repair or replace your roof before more damage occurs. In amount, ask the roofing inspector for particular information that support his or her conclusions about the condition of the roofing system and about exactly what caused its damage or wear.