Do blood cells have a rigid cell wall

What produces a record of seismic waves? richter scale seismogram barometer seismograph

A50.0-n box is sliding on a rough horizontal floor, and the only horizontal force acting on it is friction. you observe that at one instant the box is sliding to the right at and that it stops in 2.25 s with uniform acceleration. what magnitude force does friction exert on this box

In what direction does the medium move relative to the direction of the wave? explain.