Question: Solving ODE system

Hello!

I'm trying to solve numerically an ODE system with piecewise. And this piecewise is very important for this task.

This system describes behavior of a pulley with friction. There are some constants: m, c, g, mu and J. Values of this constants are not important.

> sys := m*a(t) = piecewise(a(t) < a0, F0*time, a(t) >= a0, 0), v(t) = diff(x(t), t), a(t) = diff(v(t), t);
> m := 5; F0 := 10; a0 := 5;
> initialconditions := x(0) = 0, v(0) = 0;
> dsolve({sys, initialconditions}, numeric);
Error, (in dsolve/numeric/DAE/explicit) unable to obtain the standard form of the DAE system due to the presence of leading dependent variables/derivatives in the piecewise: -5*a(t)+piecewise(a(t) < 5, 10*time, 5 <= a(t), 0)

What can I do with this? Can I use another Maple-function to solve this ODE or is there no possibility to solve such equations numerically?

Thank you!