Question

a 4.50 kg mass traveling east at 5.0 m/s has a head-on elastic collision with a 1.5 kg mass traveling west at 3.0 m/s. find the velocity of each mass after the collision.
my work so far:
vif= (4.50-1.5/4.50 + 1.5) x2
v2f= (2m1/4.50+1.5) x 2
I don't get the right answer when I use these formulas, and I wondering what the correct formulas would be......and maybe show the plugging in of the numbers in the formulas if possible?

Answer 1

east momentum positive

initial
4.5 * 5 - 1.5 * 3 = 18

final
4.5 V1f + 1.5 V2f = 18

now energy (elastic means same before and after) (never happen:)

initial
(1/2)4.5(25) + (1/2)1.5(9)
= 63 Joules
after
(1/2)4.5(V1f)^2 + (1/2)1.5(V2f^2) = 63

there you have 2 equations and two unknowns
substitute
V2f = (18 - 4.5 V1f)/1.5
into your energy equation and solve