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How It Works
A moment (M = F · d) measures the turning effect of a force about a pivot point. The larger the force or the longer the lever arm (perpendicular distance), the greater the moment. This principle explains why a longer wrench makes it easier to loosen a bolt.
Example Problem
A 40 N force is applied at the end of a 0.25 m wrench. What moment does it produce?
- M = 40 × 0.25 = 10 N·m
That 10 N·m of torque is what you would read on a torque wrench.
Frequently Asked Questions
What is the difference between moment and torque?
In physics they are the same concept (force times perpendicular distance). Engineers sometimes use “torque” for rotation about an axis and “moment” for bending effects, but the formula M = F·d applies to both.
How do you increase the moment without increasing force?
Increase the lever arm (distance). Using a longer wrench or moving the force application point farther from the pivot achieves a greater moment with the same force.
What units are used for moment?
The SI unit is the newton-meter (N·m). In imperial systems, foot-pounds (ft·lbf) or inch-pounds are common, especially in automotive and construction contexts.
Related Calculators
- Torque Calculator — another way to calculate rotational force.
- Force Equation Calculator — find force from mass and acceleration.
- Stress & Strain Calculator — analyze internal forces in materials.
- Work Calculator — calculate work done by a moment over an angular displacement.
- Power Calculator — find power from torque and rotational speed.
- Force Unit Converter — convert between newtons, pounds-force, and other force units.
Reference: Lindeburg, Michael R. 1992. Engineer In Training Reference Manual. Professional Publication, Inc. 8th Edition.