# Moment of a Force about a Point

Moment of a Force about a Point

This Demonstration shows how to find the torque, or moment of force, exerted by a rope on a boom about the point . The torque is a vector quantity, usually written . You can vary the force and the distance . When distance is expressed in meters (m) and force in newtons (N), the torque or moment has the dimension newton-meters (Nm).

AB

B

τ

BC

To find the moment about , multiply the magnitude with the unit vector from to . Next, use the position vector from to the tension . Finally, the torque about is given by the cross product

B

C

A

B

CA

B

τ=rF.