Consider the redox reaction below.

Upper Z n (s) plus 2 upper H upper C l (a q) right arrow upper Z n upper C l subscript 2 (a q) plus upper H subscript 2 (g 0).

Which half reaction correctly describes the oxidation that is taking place?
Upper Z n superscript 2 plus (s) plus 2 e superscript minus (a q) right arrow upper Z n (s).
Upper Z n (s) right arrow upper Z n superscript 2 plus (a q) plus 2 e superscript minus.
2 upper H superscript plus, plus 2 e superscript minus right arrow upper H subscript 2.
Upper H subscript 2 plus 2 e superscript minus right arrow 2 upper H superscript plus.

(newtons first law)

conservation of momentum law states :

momentum before collision = momentum after collision

momentum p (kg-m/s)= mass * velocity

say moving car=1 000 kg, velocity = 10 m/s then p = 1 000*10= 10 000 kg-m/s

say still car = 2 000 kg, velocity = 0 m/s then p = 2 000* 0 = 0 kg-m/s

total momentum prior to collision = 10 000 + 0 = 10 000 kg-m/s

momentum after collision = 10 000 kg-m/s

mass now = 1 000 kg+2 000 kg = 3 000 kg

10 000 = 3 000 kg* velocity m/s

10 000/3 000 = velocity

3.33 m/s = velocity after collision

an impulse is a force applied over time , momentum is exclusive of external forces and a perfect collision is implied