# Efficiency

The efficiency of a trebuchet is a measure of how well the trebuchet performed compared to an
ideal trebuchet. VirtualTrebuchet has two
types of efficiency, **Energy Efficiency**, and **Range Efficiency**.

In the case of finding **Energy Efficiency**, an ideal trebuchet is one that converts
all its potential energy before the
launch onto kinetic energy and potential
energy in the projectile at release. The expression for **Energy Efficiency**,
η`energy`

, is,

Since the ideal trebuchet gives all its energy to the projectile, the efficiency can be rewritten as,

A trebuchet with good **Energy Efficiency** does not necessarily shoot very far
because the equation for **Energy Efficiency** ignores direction the projectile is
launched. The projectile could be launched straight up so that it lands right back on the
trebuchet, and the trebuchet may still have a good **Energy Efficiency**. This is why
there is also **Range Efficiency**. For **Range Efficiency**, the ideal
trebuchet is one that gives all its initial potential energy to the projectile, and launches it at
45° from horizontal. 45° is not usually the ideal release angle for a trebuchet, but that is
because the projectile usually gains some extra velocity by staying in the sling longer. However,
for a given launch velocity, 45° is the optimal angle to use to get the projectile to shoot the
farthest possible. The ideal trebuchet ignores air resistance. The expression for
**Range Efficiency**, η`range`

, is,