Answer:
workers may be replaced by machines.
Step-by-step explanation:
Potential output is not purely a physical measure based on the number of workers and existing factories because: workers may be replaced by machines.
Economists define potential output as what can be produced if the economy were operating at maximum sustainable employment, where unemployment is at its natural rate.
Output in economics is the "quantity of goods or services produced in a given time period, by a firm, industry, or country". This will include output both by workers and machines