Question

Betty Bodycheck (mB = 55 kg, vB = 22.0 km/h in the positive x-direction) and Sally Slasher (mS = 45 kg, vS = 28.0 km/h in the positive y-direction) are both racing to get to a hockey puck. Immediately after the collision, Betty is heading in a direction that is 76.0° counterclockwise from her original direction, and Sally is heading back and to her right in a direction that is 12.0° from the x-axis.

What are Betty and Sally's final kinetic energies?

I got these:
V Betty = 5.51 m/s
V Sally = 5 . 99 m/s

I used the formula
k = 1/2 * m * v^2

I got these:

K Betty = 834.90 J
K sally = 807 J

I thought that i got the right answer but the book has the answer and it is Betty : 1.55kJ and Sally = 649 J


What is the correct answer?

I need to get the answer of the book

What I need to do?

Answer 1

55*22 = 1210 = 55 Vb cos 76+ 45 Vs cos 12
45*26 = 1260 = 55 Vb sin 76 - 45 Vs sin 12

1210 = 13.3 Vb + 44.0 Vs
1260 = 53.4 Vb - 9.36 Vs times 44/9.36

1210 = 13.3 Vb + 44.0 Vs
5922 = 251 Vb - 44.0 Vs
-------------------------
7132 = 264.3 Vb
Vb = 27 km/hr = 7.5 m/s humm, we disagree

Answer 2

Keb = (1/2)55 (7.5^2) = 1545 J = 1.55kJ
I agree with your book :)

Answer 3

Thanks man, you are awesome