Cinq heure et demi

Question

I don't understand why it's necessary to use "du matin" after Il est cinq heure. Since we are using the 24 hour clock isn't it understood that cinq heure would imply 5 am and not 5 pm. I would think it appropriate to say Il est cinq heure et demi dans l'apres-midi but not for the morning. I only asked because I got it wrong on the quiz.

Accepted Answer

Bonjour à tous,
This lesson has been reworked and the questions from the kwiz have been updated to include a hint as to which "clock" (12 hr clock or 24hr clock) to use when necessary. We hope it clarifies any ambiguity from these lessons/questions regarding AM vs PM, 12 vs 24 hour clock :).
We hope this is helpful.
Bonne journée !

Answer

If everyone used the 24 hour clock this would be correct and you would be understood.

In practice, some use only the 12 hour clock, some use both. Exclusive use of the 24 hour clock is usually only in “time-critical” roles eg military, train-driving etc when it is known everyone is always using the 24 hour clock.

Unless the context makes it clear, it is necessary to specify - such as in a question that asks you to give a specific and unambiguous answer. This is the same in English.

Without context, nobody is certain you are using a 24 hour clock until you say a time between treize heures et minuit - and many French people do indeed “use” a 12 hour clock expression until midi, and a 24 hour clock expression from midi to minuit. (I have a friend who is a retired French international train driver - he insists on using the 24 hour clock exclusively, and he is regularly gently mocked by family and friends for doing so)