[Frekby]

Hello, how does the value of the derivative affect the values of the source itself for a solid body. I enter a source of type a*(drho/dt) and the derivative dS=a. But at the same time, I have cases when drho/dt=0 and the source will also be zero, but the derivative remains equal to "a", in the end, whether the source will be equal to 0 or not. Is it necessary to reset the derivative when drho/dt=0