Hi, AC. Yes, I understood what I wrote. Where the exponent in a function is a constant (in this case 2), that function is polynomial. An exponential function has the parameter in the exponent. The energy in a collision is not an exponential function of the speed. Sheesh, Slashdot used to be populated with geeks!
You can brush up yourself, at http://mathworld.wolfram.com/ExponentialGrowth.html