Torque is the rotational force that causes an object to rotate around an axis, measured as the product of force and the perpendicular distance from the axis of rotation.

Torque

Torque is a fundamental concept in physics that describes the rotational force acting on an object. Just as linear force causes objects to move in straight lines, torque causes objects to rotate or twist around a fixed point or axis.

Basic Principles

The magnitude of torque (τ) is calculated using the formula:

τ = F × r × sin(θ) where:
F is the applied force
r is the distance from the rotation axis to the point where force is applied
θ is the angle between the force vector and the lever arm

Applications

Engineering

Torque plays a crucial role in various mechanical engineering applications:

Engine performance measurement
Screwdriver design and operation
Robot joint mechanics
Gears power transmission systems

Everyday Examples

Torque is present in many daily activities:

Opening a door (force applied perpendicular to door)
Tightening a bolt with a wrench
Pedaling a bicycle
Steering wheel operation

Importance in Physics

Torque is closely related to several other physical concepts:

Measurement

Torque is typically measured in:

Newton-meters (N⋅m) in SI units
Pound-feet (lb⋅ft) in imperial units
Dynamometer devices are used for precise measurements

Equilibrium

An object is in rotational equilibrium when:

The sum of all torques equals zero
This principle is crucial in Structural engineering and Architecture

Advanced Concepts

Understanding torque is essential for:

Historical Development

The concept of torque has evolved from:

Ancient understanding of levers and wheels
Archimedes principles
Modern mathematical formulations by Newton and others

This fundamental physical quantity continues to be essential in modern technology and engineering applications, from the smallest microelectromechanical systems to the largest industrial machinery.