A marble moving with some velocity collides perfectly elastically head-on with another marble at rest having mass 1.5 times the mass of the colliding marble. The percentage of kinetic energy by the colliding marble after the collision is : 

60

Since the collision is head-on-collision,

Therefore, M₁V₁ + M₂V₂ = (M₁ + M₂)V'

MV + 0 = (M + 1.5M)V'

MV = 2.5MV'

V' =  0.4 m/s  

Initial kinetic energy = 1/2 mv² = 0.5 mv²

Final kinetic energy = (1/2)(2.5)(0.4)²

                                 = 0.2 mv²

Percentage of kinetic energy = Difference in kinetic energy/Initial kinetic energy

= (0.5 - 0.2) mv² / 0.5 mv² ×100

= (0.3/0.5) × 100

= 0.6 × 100

= 60 J