A1 mechanic question

is this right?
so if an object goes up it will have a - 9.8 the V=0 and U= (a value)
but if a object falls down it will have 9.8 the U=0 and V = (a value )

If you are asking this, then you are missing the fundamental idea you are free to choose which direction you choose to be the positive one.

If upwards is your positive direction, then g=-9.8 since it acts in the opposite direction.
If downwards is your positive direction, then g=9.8 since it acts in the same direction.

The choice is up to you to make. One setup is more motivated than the other depending on the problem.

E.g. if an object is falling down then you may want to say downwards is your positive direction in which case a=9.8, but there is no problem going the other way and sticking to a=-9.8.

in most cases yes. you just need to make sure for the 2nd one that it will have an initial velocity of whatever is given in the question.

so if the question tells me a ball is falling vertically down with a speed of 2, we assume that speed is the final and the initial is 0?

That doesn't make a lot of sense in isolation. At what point does it have the speed of 2? Since gravity is always acting, speed is not constant throughout the motion

a small stone mass 400g projected vertically upwards with speed 10ms and it experiences resistance of N