Hot liquid mixed with a cold liquid

[Elena14]

My textbook says - When a hot liquid is mixed with a cold liquid, the temperature of the mixture -
"is undefined for some time and then becomes nearly constant".
Shouldn't the temperature first decrease and then become constant ? Why does it say "undefined" ?

 

[BvU]

The mixing process takes some time during which a temperature reading can give 'anything' between T_hot and T_cold. So it's not completely undefined.

Your perspective is apparently from the hot liquid ? Because for the cold liquid the temperature increases and then becomes constant !

 

[Elena14]

The mixing process takes some time during which a temperature reading can give 'anything' between T_hot and T_cold. So it's not completely undefined.

Your perspective is apparently from the hot liquid ? Because for the cold liquid the temperature increases and then becomes constant !

I haven't really come across this fact that the mixing process takes time. Will you please elaborate on this one?

 

[jbriggs444]

I haven't really come across this fact that the mixing process takes time. Will you please elaborate on this one?

If you have ever baked a cake, you will know that mixing is one of the steps. That step is not instantaneous.