So We Use Umbrellas Instead of Flak Helmets

rain Jan 21 1892This entry in from the January 21, 1892 issue of The Chatham Record shows how scary physics can be.

Why Raindrops Do Not Kill.

A falling body moves much more rapidly as it approaches the ground than it did when it commenced to fall. Its motion is, therefore, termed “a uniformly accelerated motion;” in other words, if a body being moving at a certain velocity at the expiration of one second from the point of time at which it was allowed to fall, it will be moving twice as fast at the expiration of two seconds, and so on. Experiments have shown that the rate per second at which bodies acquire velocity in falling through the air is thirty-two feet per second at the end of the first second after it has dropped from the hand; at the end of the next second with a velocity of sixty-four feet, and at the end of the third at the rate of ninety-six feet per second, and so on. The velocity of a body at any period of its fall may be ascertained by multiplying the rate of motion at the end of the first second by the number of seconds it has been falling. The velocity being known, the space through which it has fallen may be ascertained by multiplying the velocity of that period by the number of seconds during which it has been falling, and dividing the result by two. These rules only apply with absolute correctness when a body falls “in vacuo,” for the resistance of the air materially retards the velocities, especially when they become considerable, and when the body has great bulk in proportion to its weight. Were it not for this resistance, every raindrop, descending as it does from the height of many hundred feet, would strike with a force as fatal as that of a rifle bullet. – [Brooklyn Eagle.

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