Torque sign follows your rotation convention
- 01
The tempting model
Flipping torque signs because a force points down or left, rather than because of its rotational tendency.
- 02
Why it feels right
Force signs are tied to direction, so torque signs get treated the same way.
- 03
Where it breaks · how to catch it
Downward forces sometimes get positive and sometimes negative torque in the same equation.
- 04
The correct model
Choose clockwise or counterclockwise positive. Each torque sign depends on which way that force tends to rotate the object about the axis.
- 05
Repair · see it, then test it
worked example A downward force on the right end of a beam about a center pivot produces which sign if counterclockwise is positive?
Tempting move
Positive because down is chosen positive.
Correct move
Negative; it tends to rotate clockwise.
Test the repair ROT-07 · transferMake a fresh prediction before referring to the worked example.
Then practise it on the ladder
R40Torque sign conventionadds: Torque signs come from rotational tendency.