10KG ball travels at a speed(velocity) of 5ms and hits a 4KG balls which is travelling at the speed of 2ms and travelling to the same direction and 1st one.what are the velocities of two balls after the collision.

take e=1/2

I did this but never got the answer in the back of the book.here is how i did

it

M1 <<< doesn't mean M multipied by 1.it is just the notation

by using

(M1*U1 + M2*U2) = (M1*V1 + M2*V2) ---->(left drirection)

10*5 + 4*2=10*V1 + 4*v2 =

58=10*V1 + 4*v2 ------ (1)

using e(U1+U2)=V1+V2

1/2*(5-2)=V2-V1

=(3/2)=V2-V1 -------(2)[!--?can somebody tell me why is this 5-2,not 5+2

even they are travelling to the same direction?(book says so,that is why i

substracted them]

(2) equation * 4

and (1)eq-multiplied (2)nd equation gives:

58-6=10*V1+4V2 - 4*V2+4*V1

52=14V1

v1=13

but that is not the answer given on the book.what is the error?

thanks.