What is the impact force produced in mutilated gears

if during the dwell period, the gear is made to rotate in the same speed as it would during mesh,would impact force be produced?

You are correct in your interpretation. This is the basis of synchromesh gears.
As long as there is a mechanism for getting two gears into the correct relative speeds then there is no impact force when the gears are meshed.
No grinding sounds or difficulties of engagement.

Not an impact force but contact is what you need to turn gears ,so the out put of the gears to what ever your putting power to is what is going to take the force or horsepower can it with stand the shockload at tne rpms. Is what you should be looking at.