public void calc_vf()
{
if (mv_vi.getUnknown() == true)
{
this.answer.setValue((vf - Math.Sqrt(vf * vf - (2 * a * x))) / a);
}
else if (mv_a.getUnknown() == true)
{
this.answer.setValue(2 * (x / t) - vi);
}
else if (mv_x.getUnknown() == true)
{
this.answer.setValue(vi + a * t);
}
else if (mv_t.getUnknown() == true)
{
this.answer.setValue(Math.Sqrt(vi * vi + 2 * a * x));
}
}
