Ben, Lauren, Koryna, & Justin: Torque Vocabulary

The lever arm is the perpendicular distance from the pivot point to the line of action of the force. The product of the lever arm times the force equals torque.

The pivot is the center point where an object rotates around and the point on which a lever turns. ·
The fulcrum is the point or support on which a lever turns. The position of the fulcrum, relative to the position of the load and effort, determines the type of lever. For example, the center of the seesaw where it turns from and where it is supported is the fulcrum of the seesaw.
The mathematical fulcrum is the center point of a system and the line of action through the force causing torque. It is in the same position as the physical fulcrum and pivot point.

The line of action of any force is the direction of the force. It goes through the point of where a force cuases the torque.

For example-if you are pushing a car northwards, then the line of action of the force you are applying on that car is north.

· Rigid-body statics: The distance between any two given points of a rigid body remains constant in time despite the influence of the external acting exert on it. For example, when someone the track team throws a javelin, the front and back points of the javelin still remain the same distance apart.

Example Problem:

· The center of mass is the unique point at the center of a distribution of mass in space that has the property that the weighted position vectors relative to this point sum to zero.

How is it related to Torque?

· In relation to torque, when an object is supported at its center of mass there is no net torque acting on the body, it will remain in static equilibrium.

· Rotational equilibrium is the state at which the rotating velocity of an object does not change. An object is in rotational equilbrium, if it is not moving or it is rotating around an axis at a constant rate. This occurs when the clockwise torque on the object is equal to the counter-clockwise torque on the object and the net torque is zero.

Concurrent forces: All forces act on the same point on a body.
Non-concurrent forces: Forces act on different points on the body.

In a situation with CONCURRENT FORCES, you can assume the body to be a point body to determine the motion of the body.
In case of NON-CONCURRENT FORCES, the body might be subjected to torques, moments etc. So, you have to consider quantities like area moments, moment of inertia etc. to determine the motion of the body.