Summary: Torque

Table of Contents
1. What is Torque?
2. Types of Torque
3. How is Torque Calculated?
4. Measurement of Torque
5. Torque in a Car
6. Applications of Torque
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What is Torque?

Torque is the measure of a force's ability to produce rotation about an axis. It is the rotational counterpart of linear force. The point or line about which rotation occurs is the axis of rotation. The tendency of a force to cause twisting is also called the moment or moment of force. The distance between the point of force application and the axis is the lever arm. A body can be in translational equilibrium (net force zero) yet still rotate if a nonzero torque acts on it.

Types of Torque

• Static torque: produces no angular acceleration.
• Dynamic torque: produces angular acceleration.

How is Torque Calculated?

Torque depends on the magnitude of the force, the length of the lever arm, and the direction of the force. Its scalar magnitude is given by τ = Fr sin θ, where r is the lever arm and θ is the angle between the force and the lever arm. Applying a force closer to the pivot requires a larger force to produce the same torque. A force applied perpendicular to the lever arm produces the maximum torque for a given force.

Measurement of Torque

The SI unit of torque is the Newton-metre (N·m). Torque can be written as the vector (cross) product of the position vector and the force, τ = r × F, so torque is a vector whose direction is determined by the vector product.

Torque in a Car

In vehicles, engines rotate about an axis and produce torque. Torque measures a vehicle's twisting power and helps accelerate vehicles and move heavy loads.

Applications of Torque

• Seesaws and wrenches
• Gyroscopes
• Pendulums or parachutes swinging
• Riding a bicycle
• Flags on masts