How do you find Final momentum when you have initial momentum and change in momentum?

When an object is not moving, it is at 0 miles per hour. When it starts to move, it may go up to 20 miles per hour. But it started at 0 miles per hour, that's why the magnitude of the initial...

It's the same as the magnitude of the initial momentum.

Darn ! I was reading this and really getting into it and planning to tackle it. But you left out how many seconds ??? The change in the body's momentum is +300 kg-m/s . Tell us how many seconds,...

p=m*v

The velocity vector can change.