Quote:
Originally posted by Randy Chase
The big difference is that which makes an arrow fly straight. The weight of the arrow is up front. If you throw an object with the weight in the front forward, the object will tend to want to follow the weight.
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To throw a rock (okay, a hammer) at this analogy, it has only a little to do with the weight.
The physical properties at work in these cases is called aerodynamics. In both cases, the center of gravity (CG) is in front of the center of pressure(CP). The aerodynamic forces act on the CP. With the CG "in front" of the CG, the object will "fly" stable. If the CG is behind the CP, the object will flip around until the CG is in front of the CP. If the CP and CG are in the came location, the object will often tumble. That's why arrows have feathers in the rear - to move the CP rearward, otherwise, the CG and the CP would be in the same spot (the weight of the arrowhead doesn't move the CG very much at all). In the case of the hammer, the CG is most likely very close to (if not in) the metal head, but the CP is near the middle of the hammers handle - to be aerodynamically stable, the hammer will fly head first.
In the case of the discussion of front/mid/rear engined cars, the aerodynamics are not playing a significant part. The rest of the analogy is good, and the intended point is good - but in this part of the analogy, it's for the wrong reason...
The rest of the discussion is just fine and makes lots of good points - I'm just being picky...
Tim Mullen - Degree in Aerospace Engineering...
