A projectile (mass = 0.17 kg) is fired at and embeds itself in a target (mass = 2.03 kg).

The target (with the projectile in it) flies off after being struck.

What percentage of the projectile's incident kinetic energy does the target (with the projectile in it) carry off after being struck?

First off is this in two dimensions? How is the percentage calculated from elastic collision or momentum theorems?

thanks for any help.