Your code is a terrible mess. As near as I can figure you just want to multiply the matching members of two lists. The random() stuff was not used at all so I removed it. The array of 17 "Particles" was not used so I commented that line out.
// const float Particles[17] = {1.0, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 6, 6.5, 7, 7.5 , 8, 8.5, 9, 9.5, 10.0};
const int MassOfParticle[10] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
const float VelocityOfParticle[10] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
float MomentumOfParticle[10];
void setup() {
Serial.begin(9600);
Serial.println("Particle Momentum; ");
for (int i = 0; i < 10; i++) {
MomentumOfParticle[i] = MassOfParticle[i] * VelocityOfParticle[i];
Serial.println(MomentumOfParticle[i]);
}
}
void loop() {
// put your main code here, to run repeatedly:
}