So, since the newtons cradle is all about the conservation of momentum. I was wondering, when one ball is released from one side at a certain velocity, why doesn't two balls at the end swing, at half the original speed?

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haruspex
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It's not just conservation of momentum. Most of the energy is conserved too. Two balls at half the speed would only be half the energy.

The usual steel balls used in the Newtons Cradle are efficiently elastic, meaning they don't lose a lot of energy as heat. This implies most of the energy is conserved. If some other non-elastic material was used, this wouldn't be the case.

why would two balls be only half the energy?

why would two balls be only half the energy?
Say the initial single ball of mass m has velocity V, and the two balls each(of mass m) have velocity V/2. Can you find out their kinetic energies and co-relate them?

Then why couldn't the other 4 balls move with velocity V/2? In this case both sides have equal kinetic energy, thereby conserving the energy in the system.

Then why couldn't the other 4 balls move with velocity V/2? In this case both sides have equal kinetic energy, thereby conserving the energy in the system.
The momentum isn't conserved in this case davenn