  A simple and physically transparent magnetoelasticity theory is proposed to
describe linear dynamics of incompressible fractional quantum Hall states. The
theory manifestly satisfies the Kohn theorem and the $f$-sum rule, and predicts
a gaped intra-Landau level collective mode with a roton minimum. In the limit
of vanishing bare mass $m$ the correct form of the static structure factor,
$s(q)\sim q^4$, is recovered. We establish a connection of the present approach
to the fermionic Chern-Simons theory, and discuss further extensions and
applications. We also make an interesting analogy of the present theory to the
theory of visco-elastic fluids.
