a = acc(x, v, t); x += v*dt; v += a*dt; t += dt;In other words, if the position and velocity steps are asymmetric, we are always limited by the less accurate of the two.
This ``reduced'' version of our integration scheme is often referred to as the Euler method. Its chief advantage is ease of programming, but it isn't very accurate. However, a simple change to the original scheme results in a method that is both simple and accurate, as we will see in a moment!