If the distance from the fulcrum doubles while the force remains the same, what happens to torque?

• A. Increases by factor of 2
• B. Decreases
• C. Remains the same
• D. Increases by factor of 4

Answer: (A)

Torque is the turning effect produced by a force and depends on how far from the pivot the force is applied, called the lever arm, multiplied by the force itself (and by the sine of the angle between the force and lever arm). So, τ = r F sin θ.

If the distance from the fulcrum doubles while the force stays the same, and the force is applied in the same direction relative to the lever arm (so the angle doesn’t change), the lever arm term r doubles and the torque doubles as well. In other words, the turning tendency increases by a factor of two because the same push now acts farther from the pivot, producing twice the rotational effect.