Why do the balls of the Newton’s cradle eventually stop?

The balls of the Newton’s cradle eventually stop because they loose energy as they collide.

The balls of the Newton’s cradle lose energy to the air as they move through it due to friction.

These balls make sound when they collide, and consequently the balls loose energy to heat upon collision.

The balls loose energy as they collide with each other and eventually stop.

Thus, we can conclude that the balls of the Newton’s cradle eventually stop because they loose energy as they collide.

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