# Projectile Type

Selecting a **Projectile** from the drop down list of projectiles will automatically
fill out the Mass of Projectile and
Projectile Diameter inputs. If
the projectile you are using is not on the list, choose the custom option.

The baseball and golf ball options are special cases. They each have their own curve for calculating the drag coefficient. For all the other options, the simulation uses the smooth sphere curve for calculating the drag coefficient. For more information about calculating the drag coefficient see the Projectile Drag section.

# Mass Projectile

**Mass of Projectile** is the mass of the projectile.

# Projectile Diameter

**Projectile Diameter** is the diameter of the projectile.

**Projectile Diameter** is used to calculate the
drag of the projectile.

If you want to simulate your trebuchet without air resistance, use 0.0 for the
**Projectile Diameter**.

# Wind Speed

**Wind Speed** is the wind speed in the direction the trebuchet is shooting, so if the trebuchet is shooting with the wind, the **Wind Speed** will be a positive number, and if the trebuchet is shooting into the wind, **Wind Speed** will be a negative number.