How is mercury barometer constructed ?

A  mercury barometer is a device use to measure stomspheric pressure and is constructed as following:

The position of tube creates vacuum between the closed end of the tube and liquid surface and the Mercury has high density that is why used as the liquid to measure pressure.

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.

e/c, where e is its total energy