When a small ball is lifted and then released to collide with another one. At the juncture of collision, the moving ball suddenly stops whereas the still ball at the far end will move at a velocity the same with the velocity of moving ball. This indicates transfer and conservation of momentum.
After the small ball is lifted, its potential energy increases, after it is released, its potential energy has gradually converted to kinetic energy, when it hits another ball, the latter moves and when it reaches a certain height, it stops oscillating, showing kinetic energy has gradually converted to potential energy. This indicates conversion and conservation of energy.