A competitive market begins in a situation of long-run equilibrium. Then, there is an increase in demand. Describe the process that eventually leads to a new long-run equilibrium

The increase in demand results in firms earning positive profits. In response to the positive profits, new firms enter the market, increasing short-run supply. Eventually, short-run supply has increased sufficiently to restore zero profits. At that point the market has reached a new long-run equilibrium.