Newton's Cradle explanation?

Question

I need an explanation for the Newton's cradle using the newton's third law. here is how i think it and i get confused: we try the newton's cradle only with one ball- so this ball hits another that is not moving, so the force is applied to it and the force applied back by the ball that is not moving makes the ball that was moving to stop. now the 2nd ball hits the third and the force from the third makes the second to stop. because the third doesn't have any other ball to hit (if we are using only three balls) it flies away with the same acceleration as the first ball because their masses are the same. till now i understand it. but when you try it with two balls, the force that they apply will be larger. the same thing will happen with the forces so the two balls stop, but why doesn't only the third ball move with an acceleration twice as much as when we were using one ball? what happens is two balls moving with the same acceleration as the first two.

i know that the kinetic energy and the momentum should be conserved , but i want an explanation using the newton's third law.

thank you very much

Answer 1

Because Newton's third law states that if an action were to occur between two bodies, there will be an equal and opposite reaction. When the ball is released at a height, the kinetic energy will transfer through all of the balls before hitting the final ball and causing it to swing upwards an equal amount. Remember, energy can't be destroyed, therefore it has to be conserved. When a ball hits another, it comes to a stop. The energy that the ball posses has to be transferred somehow, and this is achieved by the ball transferring all of its kinetic energy onto the next ball.

Answer 2

Newton's Cradle is "Elastic Collision" ====> Both momentum and kinetic energy are conserved. The only way that can be true is if the same number of balls bounce out at the same velocity as the number of balls that came in.

Answer 3

The cradle is an inanimate merchandise so it does not "understand" something. The Cradel is largely a seen demonstration of Newtons regulation that momentum constantly had to be conserved (as a result the balls in touch pass whilst hit) and can't be created or destroyed. In a closed device anyhow. :)