High School I don't get instantaneous impulse

[atharba]

I was reading this A-level mechanics book by L. Bostock and S. Chandler. The chapter was momentum and in it, there's a section about instantaneous impulse. It says "There are many occasions when a force acts for so short a time that the effect is instantaneous, example a bat striking a ball, in such cases, although the magnitude of the force and the time for which it acts may be unknown, there is, nevertheless, an instantaneous impulse whose value is equal to the change in momentum produced"

But since impulse is equal to "the change in momentum which it produces" then why did the book just specify that in that case the impulse is equal to the change in momentum? Shouldn't this be the case for all impulses and not just the instantaneous ones?

 

[Orodruin]

then why did the book just specify that in that case the impulse is equal to the change in momentum?

It did not, it just said that the impulse is equal to the change in momentum in that case just as in any other case - even if you do not know the force or the time over which the force acts.

 

[atharba]

It did not, it just said that the impulse is equal to the change in momentum in that case just as in any other case - even if you do not know the force or the time over which the force acts.

Thanks a lot!!