"Retro Bob" <[email hidden]> wrote in message news:[email hidden]...
Quoted message said:
OK, all you amateur physicists:
If a 155 pound mass (me) is traveling at 10 mph (on bike) and I strike an object dead on with my shoulder (roughly 2 sq inches) - what the load presented by my shoulder to the object.
A rough calculation of 150lbs concentrated into 2 sq inches tells me that the static load would be 75 lbs/inch... but obviously the 10 mph would be the key here... and I forgot more physics than I ever really understood.
I am interested in a theoritical solution Assume the body is minimially deforming, the bike and person is one unit and the object crashed into is a static wall as well.
Yeah, that's my direction too. Let's assume that the bike/rider comes to a complete stop at the impact. I know the shoulder can distort on a person... so let's make it a solid object. Assume the entire weight of the solid rider is deposited in that 2 sq in.
How close can we get to a reasonable number ?
Depends on the deformation caused by the object.
If you talk about an unmovable object: hitting that with 10mph is like jumping on it from ~1m hight.
Yeah, that's my direction too. Let's assume that the bike/rider comes to a complete stop at the impact. I know the shoulder can distort on a person... so let's make it a solid object. Assume the entire weight of the solid rider is deposited in that 2 sq in.
How close can we get to a reasonable number ? Are there other assumptions we have to make ?
The crucial assumption you have to make, which some of the previous replies have missed as well, is the amount of time it takes for the rider to come to a complete stop from the impact. If it could be assumed to be instantaneous, then the force would be infinite, so don't go there. The rider is somewhat elastic, so that will spread the energy over time. You can't ignore those considerations. Jim Smith's reply got the essence of the problem.
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David L. Johnson
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