Torque Main Page
The tendency of a force to cause an object to rotate about some axis is measured by a quantity called torque.
Torque = (Force)(Distance)
The symbol used for torque is the Greek letter tau.
When tightening a bolt or a nut a mechanic will determine the amount of torque on the bolt or nut with a tool called a torque wrench. In the United States of America the common unit for torque is the foot-pound. The SI unit is the N-m or m-N.
1 foot-pound is the amount of torque caused by applying 1 pound of force at a distance of 1 foot. The force is perpendicular to the lever arm.
The lever arm is often called the moment arm.
If the torque is in a
clockwise direction its direction is negative.
If the torque is in a counterclockwise direction its direction is positive.