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Torque & Balance Beam Lab — Meter Stick on a Fulcrum

A uniform 1.00 m meter stick (mass M_s, centre of gravity at 50 cm) rests on a movable fulcrum. Hang up to three masses, read each torque about the pivot, and find the balance condition Στ = 0. Clockwise (right side down) is positive. g = 9.81 m/s².

Fulcrum & stick

Pivot position P m Stick mass M_s kg

Positions are measured from the stick's left end (0 = left, 1.000 m = right). Lever arm r = x − P; a load right of the pivot (r > 0) makes a clockwise (+) torque, left of it a counter-clockwise (−) torque. The stick's own weight acts at 0.500 m. The tilt is a visual cue only — the stick does not actually rotate.

Hanger 1

Mass m₁ kg Position x₁ m

Hanger 2

Mass m₂ kg Position x₂ m

Hanger 3

Mass m₃ kg Position x₃ m Mystery mass on hanger 3

Mystery mode replaces m₃ with a hidden value between 0.05 and 1.50 kg. m₃ and τ₃ read “?” until you press Reveal; the Στ readouts stay live.

balanced

net τ vs pivot position (current loads) P_balance

CW CCW — torque contributions about P

net τ vs pivot position (current loads) Pbalance

CW CCW — torque contributions about P

Data table

net τ vs pivot position (current loads) P_balance