Can work be done on a system if there is no motion?

there is no motion in the direction of the force, then no work is done by that force. ... But the work done on the box is zero since by moving in a straight line at constant speed, its energy is remaining the same.

you have to draw the persons position over there

i think it because equal matrices have equal dimensions, only square matrices can be symmetric. for all indices and . every square diagonal matrix is symmetric, since all off-diagonal elements are zero. in linear algebra, a real symmetric matrix represents a self-adjoint operator over a real inner product space.