A 0.20kg lump of clay slides across a horizontal, frictionless surface at 5.0m⋅s−1 and sticks to a 0.80kg wooden block that is initially at rest on the same surface. What percentage of the system’s initial kinetic energy is converted into other forms during the collision?
a) 90\%
b) 20\%
c) 80\%
d) 60\%