An 80-g particle moving with an initial speed of 50 m/s in the positive x direction strikes and sticks to a 60-g particle moving 50 m/s in the positive y direction. how much kinetic energy is lost in this collision?

The collision is a form of inelastic collision because the it forms a single mass after is collides. So it can be solve by momentum balance

(0.08 kg * 50 m/s) + (0.06 kg * 50 m/s) = (0.08 + 0.06 kg) v

V = 50 m/s

So the kinetic energy lost is

KE = 0.5 (50 m/s) ^2) * (0.14 - 0.08kg)

KE = 75 J