Originally Posted by ollopa *snip* Also, the "oz" is not the weight of the motor but the holding torque in ounce-inches. In metric this is gram-centimeters (g-cm). *snip* |
No, please... mass*distance (g*cm) does not give torque.
Force times distance does. The metric unit for torque is Nm (Newton*meter - or Ncm if you like). g-cm, kg*cm, kg*m etc are all nonsense unit.
The misunderstanding comes from the english system using the same unit (pound, lb) for both mass and force. I have seen in some places they actually separate them: pound-mass (lbm) and pound-force (lbf). This is alot clearer (to me
). Observe that 1 lbf does not equal 1 lbm (and how could they, being units of different quantities?).
This is really weird actually: an object at earth's sea level having the mass 1 lb develops a force of gravity (weight) of 1 lb. On the moon, the same mass (1 lb) would weigh 1/5 lb. So there 1 lb 'equals' 0.2 lb. The same problems arises when you try to calculate horizontal forces here on earth.
When I see the amount of questions on this board concerning torque and force I wonder if it isn't time for the US to switch to the metric system also, to get rid of these misunderstandings...
Arvid