Cue Column:

• Vector formula?
• Scalar form?
• When is torque zero?

Notes: Torque: tau = r x F. Magnitude: tau = rF*sin(theta), where theta is the angle between r and F.

tau = $r_{perp}$ * F = r * $F_{perp}$ (moment arm method).

$tau_{net}$ = I*alpha (Newton's second law for rotation).

Torque is zero when: (a) F = 0, (b) r = 0 (force at axis), or (c) F is parallel to r (sin(0) = 0).

Sign convention: Counterclockwise = positive (right-hand rule). Be consistent throughout the problem.

Summary: Torque causes angular acceleration. It depends on where and in what direction the force is applied, not just its magnitude.