Glossary

A Newton meter (N·m) is the SI (International System of Units) measurement for torque, which is the rotational equivalent of force. It represents how much rotational force (moment) is applied around an axis, such as when tightening a bolt or turning a wrench.

By definition, one Newton meter is the torque produced by a force of one Newton acting perpendicularly at a distance of one meter from the axis of rotation. In equation form, torque (τ) is expressed as:

τ = F × r

where:

- τ = torque (in Newton meters, N·m)

- F = force applied (in Newtons, N)

- r = perpendicular distance from the axis of rotation (in meters, m)

For example, if you apply a force of 10 Newtons at the end of a 0.5-meter-long wrench, the torque you generate is:

τ = 10 N × 0.5 m = 5N\cdotpm

This means you’re applying a twisting moment of 5 Newton meters about the bolt’s axis.

In everyday terms, torque describes how much twisting force you’re applying. A higher torque value means a stronger rotational effect—tightening a bolt more firmly, turning a motor shaft harder, or accelerating a wheel faster.

To visualize the relationship:

- A Newton (N) measures linear force (how hard you push or pull).

- A Newton meter (N·m) measures rotational force (how hard you twist).

Torque is also commonly expressed in pound-feet (lb·ft) or inch-pounds (in·lb) in imperial systems. The approximate conversions are:

- 1 N·m ≈ 0.738 lb·ft

- 1 lb·ft ≈ 1.356 N·m

In engineering, N·m is the standard unit for specifying tightening torque for bolts, nuts, and fasteners, ensuring the proper clamping force without over- or under-tightening.