# Pivot to Arm CG

Pivot to Arm CG is the distance between the pivot point and the center of gravity of the arm.

The center of gravity of the arm is the average location of the gravitational force acting on the arm. If the arm has a uniform cross-section along its length, then its center of gravity will be located exactly at the center the arm.

For a non-uniform arm, the center of gravity can be found by breaking the arm up into simple shapes, finding the center of mass of each one, and taking the mass-weighted average of the different parts. See the Arm Example Calculations.

Alternately, the center of gravity can be found by hanging the arm horizontally from a string, and moving the string along the arm until it balances. It will balance when the string is at the center of gravity.

For the best performance, the center of gravity of the arm should be as close to the end of the arm that the weight is attached to as possible.

Note: When Auto Calculate is checked, the arm is assumed to have a uniform cross-section and the Pivot to Arm CG will be calculated automatically.

 Units English (feet)English (inches)Metric Length of Short Arm ft Length of Long Arm ft Length of Sling ft Length of Weight ft Height of Pivot ft Uniform arm Mass of Arm lb Inertia of Arm lb·ft² Pivot to Arm CG ft Mass of Weight lb Inertia of Weight lb·ft² Projectile BaseballGolf BallPumpkinCowCustom Mass of Projectile lb Projectile Diameter ft Wind Speed ft/s Release Angle ° Play speed: 1x Link to save this trebuchet

## VirtualTrebuchet 2.0

VirtualTrebuchet is a web based trebuchet simulator that will allow you to quickly evaluate different trebuchet configurations.

1. To begin, enter the parameters of your trebuchet in the input boxes.
2. Next, press the "Simulate" button located under the inputs.
3. Finally, watch your trebuchet go.