TORQUE OR MOMENT OF A FORCE

Definition 

It is the turning effect of a force about the axis of rotation. 
Formula 
Torque = force x moment arm 
                t =f x d 
Unit 
Its unit is N-m. 

TYPES OF TORQUE 

Torque or moment may rotate a body in clock wise or anti clock wise direction. 

NEGATIVE TORQUE 

The clock wise torque is called negative torque. 

POSITIVE TORQUE 

The anti clock wise torque is called positive torque. 
Notation It is denoted by the Greek letter t (tau) 
Formula 
Torque = Force x moment arm. 
                        t= F x d 
Unit The unit of torque is (N-m) 
Nature 
It is a vector quantity. 

MOMENT ARM 

Definition 
The perpendicular distance between the line of the force and the axis of rotation is called the moment arm. 
Notation 
It is denoted by d. 

FACTORS ON WHICH TORQUE DEPENDS

 Torque depends upon two factors. 
1. Magnitude of the applied force. 
2. The moment arm Torque increases with the increase of force. Torque is directly proportional to the applied force. Torque is directly proportional to the moment arm. 

PRINCIPLE OF MOMENT

Statement 

According to the principle of Moment -If a system is in equilibrium under influence of some Torques then the sum of clock wise torques is equal to the sum of anti clock wise torques i.e. 

Mathematically 

In Equilibrium position. 

Clock wise torque = Anti clock wise torque.