# how fast is baseball sized hail going, when it hits the ground?

We had a storm last night and some areas had baseball sized hail.
How fast was it going when it hit the ground, or a car windshield?

Thanks.
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Commented:
It's based on several things including the atmospheric pressure and shape, but assuming the hailstone is roughly a perfect sphere, the equation is v = sqrt((0.667*g*diameter*dHail)/(drag*dAir))
g = 980 cm/s (gravitational constant)
diameter = 7.5cm (baseball)
dHail is density of ice or .917 g/cm^3
dAir is air density (usually around .00129 g/cm^3
drag is a constant 0.83
Converting to mph gives
v = 26.67*sqrt(diameter)
So baseball sized hail should be going about 46 mph when it lands.

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Commented:
I used a 3 inch diameter baseball. Apparently, they are more like 2.75 inches, so they should be going more like 44.2 mph.
Author Commented:
well, I read that a car wreck head-on at 35 mph is enough to cause death.

So can it be assumed that these 44-44 mile per hour, hail would break a car windshield and put dents in car hoods?
Commented:
Certainly could. Hail is hard. If a baseball hit over a fence can shatter a windsheild, then ice certainly could (it's denser). Now, if a hailstone isn't a sphere, it will usually fall more slowly. Also, hail often has a shape that makes the density smaller which would slow it down as would updrafts. So it can go much slower.

By the way, the Wikipedia article on hail terminal velocity has an obvious mathematical fallacy, I'm addressing it now.
Author Commented:
in my area we had small hail, and the wind blew the ice against the house windows (maybe marble size or smaller).
Author Commented:
thanks.
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