# Perfectly competitive constant MC Questions [closed]

If I have a market in which I have constant MC, no fixed costs, and perfect competition- when would it make sense for a new firm to enter the market(granted they have the same technology)? Would I need more information about the market?

also would the cost curves for an individual firm be 1 line since $$AC=MC=AVC$$ and $$MR=MC$$ and $$P=MC$$ under perfect competition, leading to $$P=MC=AVC=AC=MR$$

and for the market

Supply would be perfectly elastic and demand being a downward sloping curve.

## closed as unclear what you're asking by Bayesian, Adam Bailey, dismalscience, Maarten Punt, EnergyNumbersApr 17 at 10:19

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• Can you provide more information, like an attempt at a solution? – user43395 Apr 12 at 17:54
• You should provide an attempt of solution – Pedro Cavalcante Apr 12 at 19:25

During a shortage, it gets even weirder. Whether or not firms enter the industry depends on the location of the ATC curve (which is why I did not draw it in the above graphs). If $$ATC < P_F$$ at $$Q_F$$, firms would enter since profits are possible and people will buy the good they produce. If $$ATC = P_F$$ at $$Q_F$$, there is no telling whether firms will enter, since they will all be indifferent.
And if $$ATC > P_F$$ at $$Q_F$$, whether there is a surplus or shortage, firms will drop dead like flies until not a one is left. If the good being produced is of any real import, the government would probably offer subsidies to incentivise the production of the good.
So, to answer your question - it would make sense for you (a firm) to enter if $$Q and $$ATC < P_F$$ at $$Q_F$$. You could also enter when $$Q\ge Q_M$$, but then your success or failure would be left up to chance or other factors as consumers decide whether to buy your product or your competitor’s identically-priced product.