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Message: <blockquote data-quote="El Mahdi" data-source="post: 5330438" data-attributes="member: 59506">Because one of the determiners of force is acceleration, and velocity is determined by acceleration over time, and increases exponentially over time (distance). The average effect of earths gravity on the acceleration of a falling obect is 9.8 m/s2 (per second per second), or 32.18 ft. per second per second. Over the time of a fall, velocity increases exponentially, not linearly - such as after 1 second of falling, a body would have approximately* travelled 32.18 ft; after 2 seconds, 128.77 ft; after 3 seconds, 289.62 ft. etc. - up to the teminal velocity of the object in the specific medium (in average atmosphere, after about 15 seconds - at higher altitudes, a little longer - but terminal velocity is determined by the point at which drag equals gravity, causing acceleration to cease and velocity to remain constant - *the distance travelled isn't exact since drag increases as velocity increases and acts as a damper on acceleration). The equation for force is: F=ma (or Force equals mass times acceleration). Not exact numbers, but enough to get the idea: The force of a 100kg person on impact after a fall of 10ft (approximately 1/2 second falling time), is approximately 245 newtons (or joules). After 1 full second (32.18 ft.), the force at impact is now approximately 980 newtons (joules). After 2 seconds (128.77 ft.), the force at impact is now approximately 3,920 newtons (joules). So, Force is determined by mass and acceleration, and acceleration is exponential over time (per second per second) - thus Force increases exponentially over time (not linearly). This also shows why 30 ft. is a pretty good cut-off point for survivability, as the force at impact is almost certain to be catastrophic. <img src="http://www.enworld.org/forum/images/smilies/glasses.png"  class="smilie" loading="lazy" alt="B-)" title="Glasses    B-)" data-shortname="B-)" /></blockquote>

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