No - only a different way of thinking about it. According to Newton's classical formulation of his second law, F = dp/dt. Therefore, calculate the final momentum minus the initial momentum and divide by the time interval. Another way of formulating it is: F = d(mv)/dt. Since mass does not change significantly at the macroscopic level, F = m*dv/dt. You should recognize this instantly as the textbook version of the second law, F = ma. It's just that Newton did not formulate it in this way. Thus, you could also calculate the change in velocity divided by the time interval and multiply that by mass. In other words, F = (500 kg)(20 m/s)/0.1 s.