When a force is applied on a door handle, it tends to turn (open or close) the door about the hinges. This rotating or turning effect of a force about a fixed point or fixed axis is called moment of force about that point . This moment of force, i.e., the turning effect is maximum if the applied force is perpendicular to the plane of the door and the point of application is the farthest from the hinges. Therefore, the moment of for ce is measured by the product of the magnitude of the force and the perpendicular distance between the fixed point or the fixed axis and the line of action of the force. The moment of force , also called torque , is a vector quantity and is given as a cross product of the force vector ,\(\vec{F}\)and the radius vector, \(\vec{r}\) as, \(\vec{τ}\) = \(\vec{r}\) × \(\vec{F}\) and the magnitude of moment of force (torque) is given by τ = rF sinθ = F. d Here, this τ represent moment of force (torque) , also called (tau). Note - if the perpendicul...