knock vs impinge on

knock is a noun but impinge on is not a noun.

Word	Noun	Adjective	Verb	Adverb
knock	Yes	No	Yes	No
impinge on	No	No	Yes	No

As verbs, impinge on is a hypernym of knock; that is, impinge on is a word with a broader meaning than knock:

Other hypernyms of knock include collide with, hit, run into, strike.

knock (noun)	impinge on (noun)
the act of hitting vigorously
negative criticism
a vigorous blow
the sound of knocking (as on a door or in an engine or bearing)
a bad experience

knock (verb)	impinge on (verb)
find fault with; express criticism of; point out real or perceived flaws	hit against; come into sudden contact with
knock against with force or violence
rap with the knuckles
deliver a sharp blow or push
make light, repeated taps on a surface
sound like a car engine that is firing too early