If the impulse is 25 N-s, then so is the change in momentum.
The mass of the ball is extra, unneeded information.
Just to make sure, we can check out the units:
<u>Momentum</u> = (mass) x (speed) = <u>kg-meter / sec</u>
<u>Impulse</u> = (force) x (time) = (kg-meter / sec²) x (sec) = <u>kg-meter / sec</u>
Answer:
Two equal and opposite parallel forces not acting along the same line, form a couple. A couple is always needed to produce the rotation.
For example, turning a key in a lock and turning a steering wheel.