If the Riemann variants are known, how can we compute the mass – mot

1.	If the Riemann variants are known, how can we compute the mass – motion velocity u?
A.	\(\frac {J_++J_-}{2}\)
B.	\(\frac {J_+-J_-}{2}\)
C.	\(\frac {J_+×J_-}{3}\)
D.	\(\frac {J_+×J_-}{6}\)
Answer» B.

Discussion