physics question?

Question

A 0.446-kg puck, initially at rest on a frictionless horizontal surface, is struck by a 0.313-kg puck that is intitially moving along the x-axis with a velocity of 3.18 m/s. After the collision, the 0.313-kg puck has a speed of 2.18 m/s at an angle of 37 degrees to the positive x-axis.

(a) Determine the velocity of the 0.446-kg puck after the collision.

(b) Find the fraction of the kinetic energy lost in the collision

i got 1.44 m/s as the velocity but that answer is wrong i dont know what i did wrong

Answer 1

The center of mass continues along the x axis. Any y velocity after collision must cancel

0.313*2.18*sin(37)-0.446*v*sin(th)=0

The center of mass on the x axis is
0.313*3.18=
0.313*2.18*cos(37)+0.446*v*cos(th)

v is the speed of the 0.446 kg puck and th is the angle w/r/t x

solve for v and th
v*sin(th)=0.920723

v*cos(th)=1.00986

tan(th)=0.920723/1.00986
th=42.36 degrees
v=1.36658 is the magnitude
and the angle is 42.36 below the horizontal

lost KE/beginning KE
0.267

j