Why heating water at 90C takes longer than heating water at lower temperatures such as 70C?
I never heard of this before. But I can't give you an answer since I don't know much about heat transfer.
Because a lower initial temperature requires more energy to reach a set point? Water heats linearly (generally) between 0C and 100C (STP) ... 4186j/C or so.
You need to show your work. We cannot give you answers.
Why do you think it takes longer?
does the specific heat capacity has something to do with this?
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