A purple ball that has a mass of 4.2 kg and an orange ball with a mass of 4.7 kg collide in an elastic collision. The purple ball is initially moving to the left with a velocity of 15 m/s. The orange ball is moving to the right with a velocity of 12 m/s. If the final velocity of the orange ball is 11.3 m/s, what is the final
velocity of the purple ball?

Hey hope you get the answer but i suck at math sorry : (

Initial velocity,  u = 4.9 m/sfinal velocity = v m/sinitial height,  h₁ =  245 m    final height, h₂ = 0a = -9.8  m/s²time taken = t secondss = ut + 0.5at²⇒  (h₂-h₁) = ut + 0.5at²⇒  0-245 = 4.9t + 0.5×(-9.8)×t²⇒ -245 = 4.9t - 4.9t²⇒ 4.9t² -4.9t -245 =0solving it, we get   t = 7.59sv  = u +  at = 4.9 -9.8×7.59 = 4.9 - 74.38 = -69.48 m/svelocity is  69.48 m/s downward