Final answer:
During an earthquake, the seismic forces are zero at the node and max at the antinode. The maximum deformation on a wave occurs at the antinode, where the amplitude is greatest, and no movement occurs at the node, hence no seismic force.
Step-by-step explanation:
During an earthquake, the seismic forces are zero at the node and max at the antinode.
The concept here is similar to the behavior of waves, where x is the maximum deformation, corresponding to the amplitude of the wave. This deformation occurs at the antinode, which is the point on the wave at either the very top or very bottom of the curve. At the nodes, there is no movement, hence the seismic force is zero. In a physical sense, for an object undergoing vertical oscillation, at its highest point (ymax), the kinetic energy and speed are zero. At ground level, the potential energy is zero, and the kinetic energy and speed are maximum, corresponding to the point of maximum deformation or amplitude.