Question

the rate of change of momentum for a fluid is m_dot*v. I'm wondering why you can do this. If F=x*y you wouldnt just say the derivative of F(x,y) = x_dot*y, so why cab u say d(mv)/dt = m_dot*v? I know Reynolds transport theorem but that still just multiplies mass flow rate by velocity. Nasa website says that m_dot already carries the time dependence but thats a very poor explanation for the same reason as aaying F_dot = x_dot*y because x_dot carries the time dependence already

Answer 1