The True Benefit of Skinnies
Originally Posted by lunatik
Pretty much the end results but with the above mentioned hoops the smaller diameter hoop will achieve its max rpm quicker. the larger will EVENTUALLY pick up to a faster velocity but we are concerned about acceleration. with equall mass but different dia. the two rolled down a slope as in an equal race the smaller one will jump ahead a little at first. its been too long since I sat in a university physics class so I can't give an inertial equation off hand. Your right just thought a little quirk needed to be added to help out.
Originally Posted by 2002_Z28_Six_Speed
Thanx for fixing me up on that one. It's been awhile since I have been in college Phyisics too but I hard to retain everything I learned.
Originally Posted by YellowMonster87
getting through highschool physics was more then enough i couldnt even imagine it on the college level. i love physics but damn its complex!!!!!
Originally Posted by 2002_Z28_Six_Speed
It probably isn't your fault. I have only meet a handful of teachers in my life who were truly talented and capable of teaching people. Most people have no idea how to convey information in an entertaining and clear manner. Almost every teacher I have ever had in my life just repeated what the book said and slapped a test in your face. Teachers are teachers only because they could never hold a job in the real world.
Launching!
Joined: May 2006
Posts: 244
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From: Madisonville, Ky
Originally Posted by 2002_Z28_Six_Speed
Thanx for fixing me up on that one. It's been awhile since I have been in college Phyisics too but I hard to retain everything I learned.
Originally Posted by Gary Z
When normal front wheels are replaced by skinnies, the weight (mass) reduction will be equivalent to the removal of some greater static mass. This becomes obvious when you consider that the total energy in a rotating wheel consists of two parts, one of which is the kinetic energy of an equivalent static mass. The other part is the rotational energy of the wheel. I have seen claims that when skinnies replace heavier wheels, each pound saved, is equivalent to the removal of two, or four or eight pounds, of static weight. I have looked unsuccessfully for verification of these claims so I am asking for help with my calculations. The largest estimate of benefit results from assuming that the wheel mass is concentrated at the rim rather than distributed throughout a solid disk. Using the rim-loaded model of a wheel, my calculations indicate that the total energy in a wheel (translational plus rotational) is exactly double the translational (kinetic) energy of an equal non-rotating mass. If the solid-disk model is used, then the rotational energy of the wheel will equal one-half the wheel’s translational energy. This suggests to me that each pound saved when skinnies replace fatties is equivalent to, at most, two pounds of static weight. My excel spreadsheet is attached. Comments and corrections would be very much appreciated.
Originally Posted by Gary Z
Lighter wheels, front or rear, will benefit acceleration by some amount greater than removing an equal non-rotating mass. I simply focused on front wheels (called "skinnies" by drag racers) because there is usually less freedom to reduce the weight of rear wheels. The exact benefit factor has undoubtedly been calculated by real physicists but I haven't been able to find their work.
