I'm stuck--can anyone help? Thanks in advance.
The total cross-sectional area of the load-bearing calcified portion of the two forearm bones (radius and ulna) is approximately 2.2 cm^2. During a car crash, the forearm is slammed against the dashboard. The arm comes to reast from an initial speed of 80 km/hr in .0047 sec. If the arm has an effective mass of 3.0 kg, what is the compressional stress that the arm withstands during the crash?
Question-Stress/Strain/Modulus...opera sheet music
Assume the forearm is pointed straight forward, so the force is directed along its long axis. Calculate the force on the arm from F=ma, with m 3.0kg, and a the acceleration 80kph/.0047sec (fix the units so it's all m/sec first). Then you have the force, and you have the cross-sectional area that's bearing that load, so F/A=P to get the pressure or stress. Maybe divide by two if there's two bones.
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