Bucket?
a 4kg ball moving at 8m/s collides with a stationary ball of mass 12 kg, and they stick and
move together, calculate the final velocity and kinetic energy lost on impact.

Final velocity=2m/s  

kinetic energy lost = 96J

Explanation:

This question is an example for total inelastic collision.

For this type of collision, the equation is,

Step1: Finding the velocity

m1v1+m2v2 =(m1+m2) vf

4*8+12*0 = (4+12)v

32 = 16v

= 2m/s

Step 2:Finding the kinetic energy

Kinetic Energy before collision=

Kinetic Energy before collision= 128J

Kinetic Energy after collison= 32J

Step 3: Finding the kinetic energy lost

Kinetic Energy lost = Kinetic Energy after collision – Kinetic Energy before collision

Kinetic energy lost=128 -32

Kinetic energy lost=96J