As of 2008, 42 people have survived a fall from a height above 10,000 feet without a parachute. Without air resistance, a person would hit the ground with a speed of 240 m/s (540 mph!). However, by placing your body in a skydiving position (see photo), you can maximize your cross-sectional area and take advantage of the drag force to limit your speed. In this position, your terminal speed will only be 54 m/s (120 mph). This is still a high rate of speed. Just imagine being in an automobile accident at 120 mph! Nevertheless, there is a higher probability of survival, depending upon what you land on. Afterall, it is not the fall that will kill you, but the impact. If you strike concrete at 54 m/s, we will say nice things about you at your funeral. You can take comfort in the fact that you won't even feel it. Contrary to popular belief, hitting water at this speed is not much better. Your body will have to displace and compress the water as you enter it. But water, and most liquids, are difficult to compress. The surface of the liquid does not "give" nearly enough to cushion your fall. It is no surprise that the survivors fell into deep snow, trees and bushes, and marsh mud. (a) Calculate the average force exerted on a 75-kg person who strikes concrete at 54 m/s and comes to rest in 0.0052 s. (b) In comparison, calculate the average force exerted on the same person who strikes deep snow at 54 m/s and comes to rest 5.7 m deep in the snow. Assume the person's deceleration is constant and the only force that acts on him when he is brought to rest is the snow. skeeze/Pixabay
As of 2008, 42 people have survived a fall from a height above 10,000 feet without a parachute. Without air resistance, a person would hit the ground with a speed of 240 m/s (540 mph!). However, by placing your body in a skydiving position (see photo), you can maximize your cross-sectional area and take advantage of the drag force to limit your speed. In this position, your terminal speed will only be 54 m/s (120 mph). This is still a high rate of speed. Just imagine being in an automobile accident at 120 mph! Nevertheless, there is a higher probability of survival, depending upon what you land on. Afterall, it is not the fall that will kill you, but the impact. If you strike concrete at 54 m/s, we will say nice things about you at your funeral. You can take comfort in the fact that you won't even feel it. Contrary to popular belief, hitting water at this speed is not much better. Your body will have to displace and compress the water as you enter it. But water, and most liquids, are difficult to compress. The surface of the liquid does not "give" nearly enough to cushion your fall. It is no surprise that the survivors fell into deep snow, trees and bushes, and marsh mud. (a) Calculate the average force exerted on a 75-kg person who strikes concrete at 54 m/s and comes to rest in 0.0052 s. (b) In comparison, calculate the average force exerted on the same person who strikes deep snow at 54 m/s and comes to rest 5.7 m deep in the snow. Assume the person's deceleration is constant and the only force that acts on him when he is brought to rest is the snow. skeeze/Pixabay
College Physics
11th Edition
ISBN:9781305952300
Author:Raymond A. Serway, Chris Vuille
Publisher:Raymond A. Serway, Chris Vuille
Chapter1: Units, Trigonometry. And Vectors
Section: Chapter Questions
Problem 1CQ: Estimate the order of magnitude of the length, in meters, of each of the following; (a) a mouse, (b)...
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