Finding 'suitable' horizontal and vertical speed from an angle - android -

im using particle system , have when creates particle passes starting x , y value , angle want shoot particle need have vertical speed , horizontal speed can can?

hack , slash of particle:

particle(int x, int y,int x2,int y2) {   this.x = x;   this.y = y;   this.state = bulletparticle.state_alive;   this.widht = max_dimension;//rndint(1, max_dimension);   this.height = this.widht; //  this.height = rnd(1, max_dimension);   this.lifetime = default_lifetime;   this.age = 0;   this.xv = x2;//(rnddbl(0, max_speed * 2) - max_speed);   this.yv = y2;//(rnddbl(0, max_speed * 2) - max_speed);   // smoothing out diagonal speed   if (xv * xv + yv * yv > max_speed * max_speed) {    xv *= 0.7;    yv *= 0.7;   } 

work out how long want particle cross whole of width, or height, use s = 0.5 * * t^2 + v0 * t work out v0, initial speed (take @ equations of motion).

if it's not accelerating or decelerating, can use s = v0 * t ...