Explain the statement: "Fixed costs exist only in the short run. In the long run there are no fixed

Starting from:

Explain the statement: "Fixed costs exist only in the short run. In the long run there are no fixed costs." why might the time frame for the short run differ from one industry to the next? Provide examples of two industries with different time frames for the short run. Explain why this is the case.

Reference: Mankiw, N.G (2015) Principles of Microeconomics. CT: Cengage Learning