Mass 1 with a unknown mass starts at rest at the top of a frictionless from a height of 13 meters. It then slides down the incline and moves over a horizontal frictionless surface and collides inelastically (head on) with mass 2 which is 25.4 kg and initially at rest. After the collision, the total kinetic energy of both masses is 64% of the initial total kinetic energy of both masses before the collision. What is the amount of mass 1 in kg?

Question

Mass 1 with a unknown mass starts at rest at  the top of a frictionless from a height of 13 meters.  It then slides down the incline and moves over a horizontal frictionless surface and collides inelastically (head on) with mass 2 which is 25.4 kg and initially at rest.  After the collision, the total kinetic energy of both masses is 64% of the initial total kinetic energy of both masses before the collision.  What is the amount of mass 1 in kg?