Terms for subject Mathematics containing and others

English	Russian
and others	и др
and the others	и другие (но не and so on)
at times ... and at other times	иногда ... , а иногда
mass and energy can be transformed into each other	в друг друга
mass and energy can be transformed into each other	друг в друга
the actions of two bodies on each other are equal and directly opposite	прямо противоположны
the case when the source and the observer are in motion with respect to each other	относительно друг друга
the missile and the target are in relative motion to each other	двигаться относительно друг друга