On 2007 Jul 6 , at 10:28 AM, Mike Millet asked:
... ft-lbs of force ... is slightly weird ...
Using "ft-lbs of force" IS very weird (not just slightly) because ft-
lbs is not a unit of force at all; it is a unit of torque. (In metric
it would be the newton-metre*.)
The unit of force in Ye Olde English mixture of units is the pound
(not the foot-pound). Similarly, the unit of force in SI is the newton
... one thing ... that was odd is the acceleration from 1-100 km/h
was a tenth of a second faster than acceleration from 0-60 mph. Any
particular reason why?
Yes! The reason is that 100 km is shorter than 60 miles.
Specifically, 60 miles is only 96.6 km. That's about 3 % percent less
so one would expect the time to be about 3% percent less (faster).
The surprise is not that it is different, the surprise is that it is
given as halof a percent when it should be more like 3%.
(By the way, did you really mean "1 to 100"? Isn't the more usual to
judge acceleration by time it takes to go from ZERO up up some higher
value, rather than from ONE up to some higher value?")
Bill Hooper
73 kg body mass
Fernandina Beach, Florida, USA
* The relationship between the newton-metre and the foot-pound is:
1 N-m = 0.738 ft-lbs
Another unit of torque, definitely NOT SI, is the kilogram-metre. In
this unit, the kilogram is meant to be a force equal to the weight of
a one kilogram mass. That weight is 9.8 newtons on the surface of the
earth( and varies slightly with location). Therefore, 1 kg(force)-
metre = 9.8 newton-metres. The kilogram as a unit of force, and the
related kilogram-metre of torque, are totally unacceptable in SI.
