Is the verb "acknowledge" a mental or physical verb?

[Yetimwork]

Is the verb "acknowledge" a mental or physical verb?

[probus]

Usually mental. In rarer contexts it means something like "greet" or "offer a hand to".

[Barb_D]

However, I have to nod or wave or something to acknowledge a person or a point made in an argument.

[emsr2d2]

When we say something like "Please acknowledge receipt of my letter", you are definitely asking for a physical acknowledgement by email, letter or possibly by phone.

[Raymott]

I was going to say that it's usually physical. You generally acknowledge something to someone else, hence making it an interpersonal action (and therefore, barring telepathy, physical). But I guess you could acknowledge something to yourself, making it purely mental.
Is there somewhere I can read about physical and mental verbs? This question would be easier to answer if we all acknowledged it to mean the same thing.
My answer relies on pages like this: What Is a Mental Verb - Ask.com

[konungursvia]

I find the mental/physical dichotomy too Cartesian, in that there must be other possibilities. To me it's a social verb, an interpersonal act of communication, regardless of the means. Do teachers really divide verbs into these 2 categories? I hope it's just at the beginner's level.

[5jj]

Do teachers really divide verbs into these 2 categories?

I have never done so at any level.

[emsr2d2]

I have never divided them into these categories nor have I heard of anyone doing so. I didn't take the OP's question to mean that he/she thought that they were two identifiable categories of verb, simply that he/she wanted to know if we considered "acknowledge" to be a mental of physical activity.