That is so weird!!! Ok, so I asked my Fiancee if an acorn could shatter a window. She is a Physics teacher. So she looked online to try and see what the average weight of one was. Basically, 1 acorn is difficult to weigh. There must be a sample of 50 or so and dividing by that number, to achieve an average weight and mass. So then she started to make a hypo scenario with s=d/t and some other formulas. Basically, the short type... She said it would be highly unlikely an acorn (A single acorn) would do it. Its terminal velocity doesn't seem to be high enough to shatter a windshield. She is saying, depending on its size, buy the time it hits the car, from its highest point till impact, it is slowing town at some point because of resistance and gravity. The higher the object, the more time it has to slow down. But it also depends on what type of oak tree the acorn came from. Then she started thinking about her mothers house. There she had a lot of Black Walnut trees. Now the weight of those and their ability of achieving terminal velocity in the beginning, would be enough to do the damage. Because of its smooth exterior coat, it cuts down on wind resistance, allowing the object to not slow down as much as it hits the impact point.

She also mentioned if there were scratches on the glass. Moderate to deep scratches would be enough to alter the surface tension of the glass, minimizing its tensile strength. As the body is loaded under stress, that stress is transmitted to the glass. Since the surface has been compromised, the surface is no longer as strong as it should be, altering the strength of the glass and shattering it.

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2011 E70 50i M Sport