Two carts are next to each other with a spring between then. Cart A is twice the mass of cart B. The spring is compressed and held by a
string. The carts are placed directly beside each end of the spring. The
string is later cut so that the spring may expand. Cart B heads to the
right with a speed of 1.5 m/s.

With what speed (in m/s) does cart A move? And direction?