Moment Vs Torque

 

What Is Torque?

Torque is the measure of the force that can cause an object to rotate about an axis. Force is what causes an object to accelerate in linear kinematics. Similarly, torque is what causes an angular acceleration. Hence, torque can be defined as the rotational equivalent of linear force.

Types of Torque

Torque can be either static or dynamic. Static torque is a torque that does not produce an angular acceleration. A few examples of static torque are as follows:
• A person pushing a closed-door is applying a static torque because the door isn’t rotating despite the force applied.
• Pedalling a cycle at a constant speed is also an example of static torque as there is no acceleration.

The drive shaft in a racing car accelerating from the start line exhibits dynamic torque because it must be producing an angular acceleration of the wheels, given that the car is accelerating along the track.

 

    

T                         The       moment of a force about an arbitrary moment center "O" can also be described by the vector equation

where  is the position vector measured from the moment center to any point along the line of action of the force vector . The directional sense of the moment is found by first aligning the position and the force vectors tail to tail, then curling the four fingers of the right hand from  to  with the thumb pointing in the direction of the moment vector. The axis of the moment vector  passes through the moment center and is perpendicular to the plane containing  and . The magnitude of moment is measured in units of force times length (e.g., lb·in or N·m).