# Torque

Torque: The twisting force

Torque is the ability of a force to change the rotational motion of a body. This twisting force is considered as a vector, meaning it has a direction as well as a magnitude. Torque can have an anticlockwise or clockwise rotation, defined to be negative and positive respectively. It can be calculated by multiplying force and distance, but only the force being applied perpendicular to the object can affect it. Consequently, using Pythagoras theorem, the force which is not perpendicular is converted to a perpendicular component using the angle produced.

The units for torque are newton-meters (Nm). Furthermore torque increases with the distance from the hinge to the point of application, so the magnitude of torque determines the acceleration of a body in motion. In a vehicle application, torque of an engine is generally the amount of useable power that is sent to the driving wheels of the vehicle. If a vehicle has to overcome inertia due to its weight, It firstly needs he torque to overcome the weight and cause it to accelerate.

Moreover if an object is in rotational equilibrium, the sum of the relative torques is equal to zero and there is no net torque on the body. In addition torque is also important for things like tightening nuts on assemblies. There are certain specifications of the tightening torque to ensure the nuts won’t come loose. Therefore Mechanical engineers often use a direct “torque wrench” that provides the direct indication of the applied torque, in order to know precise specifications.