In 1831, soldiers marched across the Broughton Bridge in England in “lock step”—that is, marching in time together. As they marched, the bridge began to bounce in time with their footsteps; the amplitude of this bouncing became larger and larger until the bridge suddenly collapsed. Explain why the lock step of the soldiers caused this collapse and why afterward soldiers were ordered to “break step,” or march at their own individual rates, as they crossed bridges.