Can Human Forearm Bones Withstand the Stress of a High-Speed Car Crash?

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SUMMARY

The discussion focuses on the ability of human forearm bones to withstand the stress experienced during a high-speed car crash. Given the parameters of a 3.0 kg arm decelerating from 80 km/h to rest in 5.0 ms, the effective compressional stress on the bones can be calculated. The total cross-sectional area of the load-bearing calcified portion of the forearm bones is approximately 2.4 cm², and the maximum compressional stress the bone material can withstand is 16 x 107 Pa. The average pressure exerted on the bones during the crash exceeds the maximum threshold, indicating that the bones are unlikely to withstand the crash forces.

PREREQUISITES
  • Understanding of Newton's Second Law of Motion
  • Familiarity with the concept of compressional stress
  • Knowledge of unit conversions to SI units
  • Basic principles of kinematics, specifically acceleration
NEXT STEPS
  • Calculate average acceleration using the formula: a = (final velocity - initial velocity) / time
  • Determine the force applied using F = m * a
  • Calculate the average pressure using P = F / A
  • Research material properties of human bones, focusing on compressional strength
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Students in physics or biomechanics, automotive safety engineers, and medical professionals interested in the impact of high-speed collisions on human anatomy.

frenchy7322
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states of matter problem, me = :confused:

Total cross-sectional area of a load-bearing calcified portion of 2 forearm bones is approx 2.4cm squared. During a car crash, the forearm is slammed against the dashboard. the arm comes to frest from intiial speed of 80 km/h in 5.0 ms. If arm has effective mass of 3.0 kg and bone material can withstand a max compressional stress of 16x10^7 Pa, is arm likely to withstand crash?

Not sure on which equation to use due to not really getting the conceptual side of the question, please help!
 
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The compressional stress is a pressure, which is a force per area. You have the cross-sectional area of the bones, so you need the force applied. You know the mass upon which the force is applied, so you need the acceleration. The average acceleration can be found from the information that the bones are brought to rest from an initial speed of 80 km/hr in 0.005 seconds. (You only care about the magnitude of this acceleration; it doesn't matter that the acceleration is negative.) Be careful about your units: everything should be converted to SI, since you want the pressure in Pascals.

How does the average pressure to which the bone is subjected during this deceleration compare to 1.6·10^8 Pa?
 

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